Bombardier Challenger 605 - Automatic Flight Control System

of the aircraft. When engaged, the autopilot controls the aircraft’s pitch and roll axes in accordance with the coupled flight director commands. Bombardier Challenger 605 - Automatic Flight Control System Page 4 AUTOPILOT (CONT'D) Operation Autopilot Pitch Trim Automatic pitch trim is enabled whenever the autopilot is engaged. The autopilot issues commands to the horizontal stabilizer trim control unit (HSTCU) to remove continuous loads from the elevator servomotor. Protracted trim operation causes the trim clacker aural to sound. Autopilot pitch trim failure is annunciated by an AP PITCH TRIM caution EICAS message. Autopilot Mistrim Conditions The AFCS continuously monitors both axes of the autopilot when it is engaged. A significant elevator mistrim condition causes the EICAS to display an AP HOLDING NOSE UP or AP HOLDING NOSE DOWN caution EICAS message (autopilot is counteracting a significant nose-up or nose-down mistrim). For a significant aileron mistrim condition, an AP HOLDING LWD or AP HOLDING RWD caution EICAS message (indicating left or right wing down) is displayed. NOTE When the autopilot is disengaged during a mistrim condition, expect an abrupt change in control force. NOTE Autopilot monitors aileron mistrim conditions but cannot change aileron trim settings. Autopilot Servomotors When the autopilot is engaged, the active pair of FCCs direct roll and pitch commands to the aileron and elevator servos, and stabilizer trim commands through the HSTCU. When a change in roll or pitch is required, the FCCs signal the aileron servo or elevator servo to bias the control cables and displace the associated control surface. The aileron servo is located on the control cable run for the right aileron. Since the left and right ailerons are normally interconnected, the servo is capable of moving both ailerons. The elevator servo is located on the left elevator cable run. Both elevators move unless disconnected. Autopilot Engagement The autopilot is engaged by pressing the AP ENG button located on the flight control panel. Autopilot engagement is indicated by the illumination of a green indicator light along each side of the AP button. In addition, an AP engage annunciation is provided on the centre of the FMA display of each PFD (see Figure 04−10−4). Bombardier Challenger 605 - Automatic Flight Control System Page 5 AUTOPILOT (CONT'D) AP Engage Button Figure 04−10−3 Once engaged, the autopilot will couple to, and follow the guidance commands from, the selected flight director. If no FD modes are commanded prior to autopilot engagement, the autopilot automatically activates, and follows guidance from the basic lateral (ROLL) and vertical (PITCH) modes. When the autopilot is not engaged, a left- or right-pointing arrow, in white, indicates which flight director the autopilot will couple to upon engagement. Autopilot Engagement Criteria The autopilot can be engaged provided the following conditions exist: • At least one yaw damper is engaged (normally, both YDs are engaged); • No faults detected in the active pair of flight control computers (FCCs); and • No significant instability exists, including: • Adverse pitch/roll/yaw rates; • G-loads exceeding predetermined values; or • Adverse pitch/roll attitudes exceeding predetermined values. Autopilot Engagement Figure 04−10−4 Bombardier Challenger 605 - Automatic Flight Control System Page 6 AUTOPILOT (CONT'D) Autopilot Disengagement Manual (Pilots Action) Disengagement The autopilot is normally disengaged by pressing the red autopilot/stick pusher (AP/SP DISC) disconnect button on the outboard horn of either control wheel. The autopilot may also be manually disengaged by any one of the following actions: • Operating either stabilizer trim switch; • Pushing the AP ENG button on the FCP; • Selecting takeoff or go-around (TOGA) button; • Switching the AFCS SEL selector to the other AFCS (1 or 2); or • Pressing the yaw damper DISC switch. Whenever the autopilot is manually disengaged (by pilot action), the PFD green engage annunciation turns red and flashes for 5 seconds, the green status indicator lights beside the AP button extinguish, and the autopilot disconnect (cavalry charge) aural sounds. The autopilot disconnect warning will automatically cancel after a few repetitions of the cavalry charge. Monitored Disengagement The FCCs continually monitor aircraft sensors, servo data, the automatic pitch trim system and internal parameters for faults. The autopilot will automatically disengage if any of the following conditions occur: • Internal FCC monitors detect a failure in any axis; • Any power source to an FCC of the active pair is lost; • Loss of either inertial reference system (IRS) system input; • Dual yaw damper failure; • Aircraft is at an excessive attitude (pitch angle beyond +25° or −17°, roll angle beyond ±45°); • Either stick shaker activates; or • Switch from one AFCS to the other. A monitored disengagement is annunciated in the same manner as a manual disengagement, with the exception that the flashing on the PFD and the aural warning will continue until cancelled by the flight crew. Pressing either pilot’s AP/SP DISC switch or TOGA button, or reengaging the autopilot, will cancel the flashing on the PFD and the aural warning. YAW DAMPER SYSTEM Description Each yaw damper is a dual-channel, fully independent yaw damper system, providing yaw damping, turn entry, steady-state turn coordination, and turn exit for the full flight envelope. The yaw dampers operate independently of the autopilot. NOTE The yaw damper will not compensate for a sustained adverse yaw created by an engine power asymmetry or improper rudder inputs. Bombardier Challenger 605 - Automatic Flight Control System Page 7 YAW DAMPER SYSTEM (CONT'D) Operation Yaw Damper Engagement The yaw dampers are engaged by pushing both YD 1 and YD 2 switch/lights on the YAW DAMPER panel. Selective engagement of the switch/lights activates the corresponding yaw damper channel. Yaw damper engagement is indicated by the absence of YAW DAMPER (status and caution) EICAS messages and PFD indications. Normally, both yaw dampers are engaged for all phases of flight. One yaw damper channel will provide adequate yaw damping and turn coordination during flight. At speeds greater than 256 kts, only one yaw damper will be active. Yaw Damper Disengagement The DISC button on the YAW DAMPER panel disengages both yaw damper channels when pressed. When both yaw damper channels are disengaged, an amber YD annunciation is displayed on the upper left side of the PFDs, and a YAW DAMPER caution EICAS message appears. A single disengaged (or inoperative) yaw damper channel is indicated by a YD 1(2) INOP status EICAS message. YAW DAMPER Panel Figure 04−10−5 Bombardier Challenger 605 - Automatic Flight Control System Page 8 YAW DAMPER SYSTEM (CONT'D) Yaw Damper Disengaged Annunciation Figure 04−10−6 FLIGHT DIRECTORS Description The flight directors (FDs) are the visual representation of the commands generated by the flight control computers. Operation Flight Director Command Bars The flight directors provide integrated pitch and roll guidance by means of magenta inverted V-shaped (V-BAR) or cross pointer (X-PTR) command bars on the ADI of the PFD. The command bars are always in view when the flight director is being used or when the autopilot is engaged. The command bars are out of view when the flight director is turned off or flagged, or when the aircraft’s attitude is extreme. The pilot can manually fly the aircraft by following the command bar guidance cues. When the autopilot is engaged, the FCCs issue steering commands to the aileron and elevator servos according to the flight director guidance instructions. Bombardier Challenger 605 - Automatic Flight Control System Page 9 FLIGHT DIRECTORS (CONT'D) Flight Director Command Bar Figure 04−10−7 Flight Director Selection There are two independent flight directors for each AFCS channel. They are designated as per the following table: Flight Director Designation AFCS CHANNEL LEFT SIDE FCC RIGHT SIDE FCC 1 FD 1 FD 2 2 FD 1 FD 2 In most flight director modes, only one FD provides guidance commands and flight mode annunciations to both PFDs. The other FD operates as a standby. This ensures that all FD mode annunciation and command cues displayed on the left and right PFD remain synchronized. At power-up, both flight directors are off. FD 1 defaults as the active flight director, following selection of any lateral or vertical mode on the FCP. When FD 1 is active and the autopilot is disengaged, a white left-pointing arrow is displayed in the FMA area of both PFDs. The right PFD also displays a green FD 1 annunciation below and to the left of the FMA area, to indicate that right side FD commands are being supplied by FD 1. Bombardier Challenger 605 - Automatic Flight Control System Page 10 FLIGHT DIRECTORS (CONT'D) Flight Director Couple Arrow Figure 04−10−8 When the autopilot is engaged with FD 1 active, a green AP annunciation is displayed on both PFDs over the left-pointing FD arrow. When the left-seated pilot has control of the aircraft, FD 1 is normally selected and all flight guidance commands are derived using the left side systems (ADC 1, IRS 1, left side navigation source selection). AP/FD Engagement Figure 04−10−9 AP/FD Transfer (XFR) Mode Selecting XFR on the flight control panel transfers to the cross-side active FD. It determines which FD guidance the autopilot will follow when engaged. The following table illustrates the PFD display based upon XFR switch selection. In addition, the green status indicator lights beside the XFR button illuminate to indicate that transfer mode is active. Bombardier Challenger 605 - Automatic Flight Control System Page 11 FLIGHT DIRECTORS (CONT'D) AP/FD Transfer Figure 04−10−10 Dual Independent FD Operation Both FDs become active and supply independent flight guidance commands to their associated PFD (dual independent operation) when in the following flight director modes: • Takeoff mode; • Go-around mode; and • Approach (APPR) mode. Bombardier Challenger 605 - Automatic Flight Control System Page 12 FLIGHT DIRECTORS (CONT'D) When operating independently, the coupled side channel supplies steering commands to the autopilot, and dual independent flight guidance computations are supplied to the flight directors (“split” flight directors). The left channel supplies flight guidance commands to the left flight director, and the right channel supplies flight guidance commands to the right flight director. In the above modes, the FD1 and FD2 annunciations are not displayed on the PFDs. Independent "Split" FD Mode Figure 04−10−11 Flight Mode Annunciator (FMA) Lateral and vertical FD modes are presented in the flight mode annunciator (FMA) displayed on each PFD. The FMA is located above the PFD ADI display. The FMA is divided into two fields, separated by vertical cyan lines. The left field displays the lateral flight director modes. The right field displays the vertical FD modes. Each field has two lines, the top indicates the active or captured mode (green), the bottom line indicates the armed modes (white). Certain conditions will trigger the use of yellow, and will be explained under each mode. FMA Active/Captured Mode Display The active/captured lateral and vertical modes are displayed in steady green text. Lateral and vertical modes that are capturing are displayed in flashing green text for five seconds, then change to steady green text. If the active lateral or vertical mode becomes invalid (sensor data), the flight control system removes the invalid steering commands from the affected flight director. A red horizontal line is superimposed over the affected active mode annunciation (e.g. ). FMA Armed Mode Display The armed lateral and vertical modes are normally displayed in steady white text in the lower portion of the lateral or vertical field. Up to two vertical modes may be armed simultaneously. Bombardier Challenger 605 - Automatic Flight Control System Page 13 FLIGHT DIRECTORS (CONT'D) Flight Mode Annunciator (FMA) Figure 04−10−12 FD Activation There are three methods to activate the flight director: • Selecting a lateral or vertical mode on the flight control panel; • Engaging autopilot; or • Pushing takeoff/go-around (TOGA) switches. FD Deactivation The flight director is deactivated with the FD button on the FCP. When the autopilot is not engaged, pressing the FD button on the offside will deactivate the offside flight director only. Pressing the onside FD button disengages both flight directors. When the autopilot is engaged, pressing the FD button on the offside will deactivate the offside flight director only. Pressing the onside FD button has no effect. The FD button is inhibited during an overspeed condition. FD Synchronization The FD SYNC switch synchronizes the FD command bar reference values to the values flown at the time of selection. The FD SYNC switch is located on the back outboard horn of the pilot’s and copilot’s control wheels. Bombardier Challenger 605 - Automatic Flight Control System Page 14 FLIGHT DIRECTORS (CONT'D) The following flight director modes can be synchronized to the current aircraft conditions when the FD SYNC switch is depressed: • FLC (indicated airspeed/Mach); • VS (vertical speed); • ALT (barometric altitude hold); • PTCH (pitch angle); and • ROLL (roll angle). When any flight director mode listed above is active, pressing the FD SYNC switch causes a yellow SYNC message to appear on both PFDs. The SYNC message will be removed when the FD SYNC switch is released. Pressing the FD SYNC switch while the autopilot is engaged releases the aileron and elevator servo clutches, which allows the flight crew to manually fly the airplane without disengaging the autopilot. The AP engage annunciation will also appear in yellow whenever the FD SYNC switch is being pressed with the autopilot engaged. NOTE While the FD SYNC switch is pressed, trimming the horizontal stabilizer will not disengage the autopilot. AP/FD Synchronization Figure 04−10−13 FD Failure If the active flight director fails, the flight director command bars are removed from both PFDs and replaced by a red boxed FD annunciation. An FD 1(2) FAIL status EICAS message may also be displayed. If the active FD fails, selecting the XFR button on the FCP deselects the failed flight director and allows the cross-side flight director to become active. Bombardier Challenger 605 - Automatic Flight Control System Page 15 FLIGHT DIRECTORS (CONT'D) Selecting the other AFCS (1 or 2) enables the second pair of FCCs, which would then allow the autopilot to be reengaged. FD Failure Indications Figure 04−10−14 Flight Director Lateral Modes There are eight flight director lateral modes (bold letters refer to the FCP button selections): • Roll • Heading select (HDG) • Half bank (1/2 BANK) • Navigation; FMS, VOR, LOC (NAV) • Approach; FMS, VOR, LOC (APPR) • Back course (B/C) • Takeoff • Go-around Lateral modes are armed or activated by push-buttons on the flight control panel or on the thrust levers. In general, deselecting the active lateral mode is accomplished by reselecting the active FCP mode push-button, or by selecting another lateral mode. Roll Mode ROLL is the basic lateral operating mode, and is automatically selected when no other lateral mode is active and the flight director is on. A green ROLL annunciation appears in the active lateral field of the FMA when roll mode is active. Roll mode generates commands to maintain a reference bank angle. If the roll attitude (bank angle) is more than five degrees from level when roll mode is selected, the FCC generates commands to maintain the bank angle. If the roll attitude is less than five degrees, the FCC generates commands to maintain heading by rolling to zero bank (wings level). Bombardier Challenger 605 - Automatic Flight Control System Page 16 FLIGHT DIRECTORS (CONT'D) The pilot flying may adjust the roll reference to a desired roll angle by pushing the FD SYNC button and manually setting a bank angle up to 30 degrees. If the pilot selects a bank angle greater than 30 degrees, but less than 45 degrees, the FD will generate commands to return to 30 degrees’ bank upon release of the FD SYNC button. Roll mode is automatically cleared by selection of another lateral mode. NOTE Roll mode is automatically selected if the data required to fly the active lateral mode becomes invalid. Roll Mode Figure 04−10−15 Heading Select Mode Pushing the HDG button on the FCP alternately selects and clears heading select mode. A green HDG annunciation appears in the active lateral field of the FMA when the mode is active. Heading select mode generates commands to capture and maintain the selected heading (heading bug). When heading mode is selected, the direction of turn will be the shortest turn to the heading bug. The desired heading can be changed by turning the HDG knob on the FCP. With heading mode active, the direction of turn will always be in the direction the heading bug is moved. The heading bug may be synchronized to the aircraft’s current heading by pressing the PUSH SYNC button in the center of the heading knob. Heading mode is automatically cleared by selection or capture of another lateral mode, or by pressing the HDG button again. Bombardier Challenger 605 - Automatic Flight Control System Page 17 FLIGHT DIRECTORS (CONT'D) Heading Mode Figure 04−10−16 Half Bank Mode Pushing the 1/2 BANK button on the FCP alternately selects and clears half bank mode. When the mode is active, a white 1/2 BNK annunciation appears to the left of the active/captured roll mode on the PFDs, and a green arc is displayed at the top of the roll scale. Half bank mode may be selected simultaneously with heading (HDG) or FMS navigation mode. When active, half bank mode (1/2 BANK) reduces the roll limit to half the normal value for the active lateral mode. Half bank mode is cleared automatically by activation of a noncompatible lateral mode (TO, GA, onside approach mode or localizer capture), or can also be cleared by pressing the 1/2 BANK button again. Automatic Half Bank Half bank is automatically selected if either flight director is selected and the airplane climbs through a transition altitude of 31,600 feet MSL, or if the airplane is above this altitude when the flight director is turned on. Half bank mode automatically clears when the airplane descends below 31,600 feet MSL. Manual operation of half bank mode overrides the FCC automatic transitions to or from half bank mode. Bombardier Challenger 605 - Automatic Flight Control System Page 18 FLIGHT DIRECTORS (CONT'D) Half Bank Mode Figure 04−10−17 NAV Mode Pushing the NAV button on the FCP alternately selects and clears the navigation mode, and causes the flight director to generate lateral commands to capture and track the active navigation source (VOR, LOC, FMS). The displayed navigation source will determine which navigation submode will be in operation. NAV Source Selection The navigation source may be selected using the PRESET NAV box or the PFD menu. • PRESET NAV box: Select desired preset NAV source by rotating the data knob on the DCP, then push the NAV SRC swap button. • PFD menu: Press MENU button on the DCP, and use the menu ADV/DATA knob to select the desired NAV source. LOC or VOR navigation source is determined by the ground station frequency set in the radio tuning window. All NAV mode annunciations appear in the lateral field of the FMA: armed modes in white, and active/captured modes in green. Captures that are inhibited due to invalid data are annunciated on the PFDs as a red horizontal line through the mode annunciation. Bombardier Challenger 605 - Automatic Flight Control System Page 19 FLIGHT DIRECTORS (CONT'D) Display Control Panel Figure 04−10−18 Navigation Source Selection Display Figure 04−10−19 Bombardier Challenger 605 - Automatic Flight Control System Page 20 FLIGHT DIRECTORS (CONT'D) VOR Navigation Mode In the VOR navigation mode, the flight director generates lateral steering commands to capture and track the selected VOR radial (inbound or outbound), using the course displayed on the active navigation source. When the NAV button is pressed and the active navigation source is VOR1 or VOR2, the VOR navigation mode is armed. The armed lateral mode field on both PFDs shows a white VOR1 (or VOR2) annunciation. When the VOR mode is captured, the armed annunciations are removed, and a green VOR1 (or VOR2) annunciation is displayed in the active lateral mode field on the PFDs. The CRS1 and CRS2 knobs, located on the FCP, provide the means to select the desired course on the left and right PFD HSI respectively. Pressing the PUSH DIRECT knob within the CRS knob synchronizes the corresponding course display, and provides a “direct-to” VOR course. VOR navigation mode is designed to permit tracking over station, and allow for course changes while tracking. When over a VOR station, the system can accept and follow a course change of up to 90°. Dead reckoning operation (based on memorized heading) is provided during VOR station passage. A white DR annunciation appears next to the active VOR mode annunciation during dead reckoning operation. When captured, VOR navigation mode is cleared automatically by selection of another lateral mode, by changing the active NAV source, or by loss of the VOR signal. VOR navigation mode can also be cleared by pressing the NAV button again. Bombardier Challenger 605 - Automatic Flight Control System Page 21 FLIGHT DIRECTORS (CONT'D) VOR Navigation Mode Figure 04−10−20 Localizer Navigation Mode In localizer navigation mode, the flight director provides lateral steering commands to capture and track the front course localizer from the active navigation source. Whenever LOC navigation mode arms, a white LOC1 (or LOC2) annunciation is displayed in the armed lateral mode field on both PFDs. When the LOC mode is captured, the armed annunciation is removed, and a green LOC1 (or LOC2) is displayed in the active lateral mode field on both PFDs. Bombardier Challenger 605 - Automatic Flight Control System Page 22 FLIGHT DIRECTORS (CONT'D) When captured, LOC navigation mode is cleared automatically by: • Selection of another lateral mode, • Changing the active NAV source, or • Loss of localizer signal. LOC mode can also be cleared by pressing the NAV button again. LOC Navigation Mode Figure 04−10−21 FMS Navigation Mode In FMS navigation mode, the flight director uses lateral steering commands from the active flight management computer (FMC) to capture and track the desired track to the “TO” waypoint. Bombardier Challenger 605 - Automatic Flight Control System Page 23 FLIGHT DIRECTORS (CONT'D) When the NAV button is pressed, and the active navigation source is FMS1 or FMS2, the FMS navigation mode arms, and a white LNV1 (or LNV2) annunciation is displayed in the armed lateral mode field on both PFDs. When the FMC capture criteria are met, the armed annunciation is removed, and a green LNV1 (or LNV2) annunciation is displayed in the active lateral mode field on both PFDs. Depending on the display selected on the PFD, a white track is displayed in PPOS format, or a magenta deviation bar is displayed in ROSE format. When captured, FMS navigation mode is cleared automatically by selection of another lateral mode, by changing the active NAV source, or by loss of FMS steering validity. FMS navigation mode can also be cleared by pressing the NAV button again. FMS Navigation Mode Figure 04−10−22 Approach Mode Approach mode is used to fly a localizer-based (ILS) or FMS-based nonprecision approach. During approach mode, the flight directors operate in dual independent mode. Approach mode is selected by pressing the APPR button on the FCP. The displayed navigation source will determine which approach submode will be in operation. ILS-Based Approach Pushing the APPR button alternately selects and clears approach mode. Approach mode localizer capture functions the same as localizer navigation (NAV) mode. Additionally, glideslope (GS) mode is armed for capture. Bombardier Challenger 605 - Automatic Flight Control System Page 24 FLIGHT DIRECTORS (CONT'D) Automatic NAV-to-NAV Transfer When a localizer-based approach is selected from the FMS and the aircraft is within 30 nm of the airport, the localizer frequency is automatically tuned and the course display is set to the appropriate inbound course. The localizer deviation scale and pointer are superimposed in cyan on the PFD HSI, and a cyan LOC1 (or LOC2) navigation source is displayed below the active navigation source (FMS 1 or FMS 2). With approach mode armed (APPR button selected on FCP) during localizer intercept, the active navigation source will automatically change from FMS to LOC (automatic NAV to NAV transfer) at localizer capture. If required, approach mode can then be canceled and navigation mode selected by pressing the NAV button on the FCP. Bombardier Challenger 605 - Automatic Flight Control System Page 25 FLIGHT DIRECTORS (CONT'D) ILS Approach Mode Figure 04−10−23 Bombardier Challenger 605 - Automatic Flight Control System Page 26 FLIGHT DIRECTORS (CONT'D) FMS-Based Approach Pushing the APPR button alternately selects and clears approach mode. The FMS-based approach mode functions the same as FMS navigation (LNV) mode. Additionally, glide path (GP) mode is armed for capture, to track the desired glide path from the FMS if VNAV is selected. Refer to the Collins FMS–6000 Flight Management System Pilot’s Guide for additional information on FMS-based approaches. Bombardier Challenger 605 - Automatic Flight Control System Page 27 FLIGHT DIRECTORS (CONT'D) FMS Approach Mode Figure 04−10−24 Bombardier Challenger 605 - Automatic Flight Control System Page 28 FLIGHT DIRECTORS (CONT'D) Localizer Back Course Mode Back course mode (B/C) generates commands to track a localizer signal using reverse-sensing. Back course mode is armed by pressing the B/C button on the FCP. Back course mode localizer capture is the same as NAV mode; B/C1 (or B/C2) shows in white in the armed lateral mode field on both PFDs. When armed, the FCC operates in a heading select submode until capture of the localizer occurs. If the back course approach is selected from the FMS, the localizer frequency is tuned automatically and the course display is set to the appropriate inbound course. With back course mode armed, the active navigation source will automatically change from FMS to LOC (automatic NAV to NAV transfer) at localizer capture. After capture, the FCC generates commands to track the reciprocal of the selected course. The front course track must be set in order to have valid B/C guidance. Capture of the back course is indicated by a green B/C1 or B/C2 in the active field of the FMA. Glideslope is inhibited when B/C mode is active. Back course mode is cleared by selecting another lateral mode, or by changing the active side navigation source or frequency. Bombardier Challenger 605 - Automatic Flight Control System Page 29 FLIGHT DIRECTORS (CONT'D) Back Course Mode Figure 04−10−25 Bombardier Challenger 605 - Automatic Flight Control System Page 30 FLIGHT DIRECTORS (CONT'D) Lateral Takeoff On the ground, pushing either TOGA (takeoff/go-around) button, mounted on the thrust levers, selects takeoff mode and clears all other lateral modes. Lateral and vertical takeoff mode selections are coincident. When takeoff mode is active, a green TO appears in the active lateral field of the FMA. During takeoff mode, the flight directors operate in dual independent mode. NOTE The autopilot will disengage whenever a TOGA button is pressed on the ground or in-flight. The autopilot visual and aural disengage warnings may be canceled by pushing either TOGA button again, or by pushing any AP/SP DISC switch. With takeoff mode selected, the heading reference is continuously set to the current aircraft heading while maneuvering on the ground. After lift-off (weight off wheels), the takeoff mode generates a heading hold command, with a five-degree bank limit, using the heading which existed at the moment of lift-off. These heading references are independent of the HDG bug. Takeoff lateral mode is cleared by selecting another lateral mode. Lateral Takeoff Mode Figure 04−10−26 Bombardier Challenger 605 - Automatic Flight Control System Page 31 FLIGHT DIRECTORS (CONT'D) Lateral Go-Around Mode In the air, pushing either TOGA (takeoff/go-around) button, mounted on the thrust levers, selects the go−around mode and clears all other lateral modes. Lateral and vertical go−around mode (GA) selections are coincident. When go−around mode is active, a green GA appears in the active lateral field of the FMA. During go-around mode, the flight directors operate in dual independent mode. NOTE The autopilot will disengage whenever a TOGA button is pressed on the ground or in-flight. The autopilot visual and aural disengage warnings may be canceled by pushing either TOGA button again, or by pushing any AP/SP DISC switch. The lateral component of go-around mode (GA) generates commands to maintain the heading that existed at the moment of GA mode activation. Go-around mode generates a heading hold command with a five-degree bank limit. This heading reference is independent of the HDG bug. Go-around mode is cleared by selecting another lateral mode. Lateral Go-Around Mode Figure 04−10−27 Flight Director Vertical Modes There are nine vertical flight director modes (bold letters refer to the flight control panel button selections): • Pitch • Altitude preselect • Altitude hold (ALT) • Vertical speed (VS) • Flight level change (FLC) • Takeoff Bombardier Challenger 605 - Automatic Flight Control System Page 32 FLIGHT DIRECTORS (CONT'D) • Go-around • Glideslope • FMS vertical navigation (VNAV) Vertical modes are armed or activated by the FCP push-buttons, a pitch wheel on the flight control panel, or by TOGA switches on the thrust levers. In general, disabling the active vertical mode is accomplished by reselecting the active FCP push-button, or by selecting another vertical mode. Pitch Mode Pitch mode (PTCH) is the basic vertical operating mode, and is automatically selected when no other vertical mode is active and the flight director is on. A green PTCH annunciation appears in the vertical active field of the FMA when pitch mode is active. When PTCH mode is active, the FCC generates commands to maintain the aircraft’s pitch angle reference. The pitch angle reference value may be adjusted by rotating the VS/pitch wheel on the FCP in the desired direction. Each click of the wheel results in 0.5 degrees of pitch attitude change. NOTE All flight director vertical modes reset to PTCH mode when the VS/pitch wheel is rotated, except if vertical speed (VS) or glideslope capture (GS) modes are active. VS/pitch wheel rotation has no effect after glideslope capture. The pilot may also adjust the pitch reference to a desired pitch angle by pushing the FD SYNC button, and manually setting a pitch angle between +20 to –10 degrees. If the pilot selects a pitch angle greater than the maximum limits, the FD will generate commands to return the pitch angle to within limit upon release of the FD SYNC button. Pitch mode is automatically cleared by selection or capture of another vertical mode. Pitch Mode Figure 04−10−28 Bombardier Challenger 605 - Automatic Flight Control System Page 33 FLIGHT DIRECTORS (CONT'D) Altitude Preselect Mode The altitude preselect mode (ALTS) causes the flight director to generate commands to capture and level off at the preselected altitude. It is comprised of armed, capture and track states. Altitude preselect mode commands are based on the coupled side barometric altimeter. The preselected altitude is set by the ALT knob on the FCP, and is displayed as a cyan digital readout on the top right corner of the PFDs, and by a cyan altitude (double-bar) bug on the barometric altimeters. The ALTS mode is automatically armed upon selection of any vertical mode, except altitude hold (ALT), vertical approach (GS or VGP), or go-around (GA) modes. When ALTS mode is armed, the FCCs calculate the capture point for the preselected altitude, while operating in the current active vertical mode. The capture point is a function of closure rate, with the capture point occurring earlier for high closure rates. A white ALTS annunciation appears in the vertical armed field of the FMA when altitude preselect mode is armed. When the airplane is in a position to capture the preselected altitude, the system generates commands to level off (capture) and track the preselected altitude. During the altitude capture sequence, a green ALTS CAP annunciation is displayed in the vertical capture field of the FMA, and the armed annunciation is removed. When the capture (level-off) is completed, the flight director generates commands to track the preselected altitude. A green ALTS annunciation remains displayed in the vertical capture field of the FMA. NOTE If the preselected altitude is changed during altitude capture, the ALTS CAP display is replaced by ALT, and a yellow ALTS annunciation is temporarily displayed in the vertical armed field of the FMA. The FCCs will continue to capture and track the original preselected altitude displayed while ALTS CAP was active. Bombardier Challenger 605 - Automatic Flight Control System Page 34 FLIGHT DIRECTORS (CONT'D) Altitude Capture Sequence Figure 04−10−29 Bombardier Challenger 605 - Automatic Flight Control System Page 35 FLIGHT DIRECTORS (CONT'D) Altitude Alert System The altitude alert system provides aural and visual indications of preselected altitude capture and tracking. It also provides aural and visual indications of altitude deviations from the preselected altitude (ALTS). The altitude alerting system processes data from the air data computers (ADCs), and is independent of the flight director or autopilot modes. Altitude alert annunciations are based on the baro-corrected altitude of the coupled side altimeter. Capture Alert At 1,000 feet prior to the preselected altitude, the preselected digital readout and bug flash, and an aural tone (C-chord) sounds. Deviation Alert If the aircraft deviates by more than 200 and/or 1,000 feet from the preselected altitude, the altitude bugs and digital readout flash yellow, and an aural tone (C-chord) is heard. Altitude alerts can be canceled by pushing the PUSH CANCEL inset of the ALT knob, or by selecting a new preselect altitude. Altitude alerts are inhibited if the glideslope (GS) or FMS glide path (VGP) is captured. Bombardier Challenger 605 - Automatic Flight Control System Page 36 FLIGHT DIRECTORS (CONT'D) Altitude Alert Annunciations Figure 04−10−30 Altitude Hold Mode Altitude hold mode (ALT) generates commands to maintain the pressure altitude at the time of selection. Altitude hold mode commands are based on the baro-corrected altitude of the coupled side barometric altimeter. When active, a green ALT annunciation appears in the active vertical field of the flight mode annunciator. Altitude hold mode is activated by pushing the ALT button on the FCP, or by changing the preselected altitude while in altitude select track mode (ALTS active). Bombardier Challenger 605 - Automatic Flight Control System Page 37 FLIGHT DIRECTORS (CONT'D) Altitude hold mode is inhibited whenever glideslope (GS) mode is active. NOTE If the ALT button on the FCP is pushed during a climb or descent, it is possible for the aircraft to temporarily overshoot the desired altitude while the FCCs compensate for the aircraft’s vertical speed at the moment of ALT mode selection. The pilot may adjust the altitude reference by pushing the FD SYNC button and manually flying to the desired altitude. The FD will generate commands to maintain the new altitude reference upon release of the FD SYNC button. Altitude hold mode may be cleared by: • Pushing the ALT button; • Selecting another vertical mode; or • Capturing an armed vertical mode. Altitude Hold Mode Figure 04−10−31 Vertical Speed Mode The vertical speed mode (VS) generates commands to maintain a vertical speed reference value. Pushing the VS button on the FCP selects the vertical speed mode. A green VS annunciation is displayed in the active vertical field of the FMA, the selected vertical speed value is displayed in cyan, and ALTS mode is automatically armed to capture the preselected altitude. The VS reference value will default to the existing vertical speed at the moment of mode selection. The VS reference value will also reset to the existing vertical speed whenever the autopilot is engaged and VS mode is active. Bombardier Challenger 605 - Automatic Flight Control System Page 38 FLIGHT DIRECTORS (CONT'D) The VS reference may be changed by rotating the VS/pitch wheel in the desired direction. The VS reference changes by ±100 fpm per click. The selected vertical speed reference is displayed on the vertical speed scale as a cyan triangular bug, and as a cyan digital readout with an up/down arrow right of the VS indication in the FMA. The pilot may adjust the VS reference by pushing the FD SYNC button while maneuvering the airplane to a new VS reference. The FD will generate commands to maintain the new VS reference upon release of the FD SYNC button. Vertical speed mode is cleared by: • Pushing the VS button on the FCP; • Selecting another vertical mode; or • Capturing an armed vertical mode. Vertical Speed Mode Figure 04−10−32 Flight Level Change Mode Flight level change mode (FLC) generates commands to maintain either the airspeed/Mach reference value, or a 100 ft/min vertical speed toward the preselected altitude, whichever yields the greater closure rate to the preselected altitude. Pushing the FLC button selects flight level change mode. A green FLC annunciation is displayed in the active vertical field of the FMA, and ALTS is automatically armed to capture the preselected altitude. When FLC mode is selected manually, or by the FMS, the airspeed/Mach reference displayed on the PFDs (speed bug) is automatically set to the aircraft’s current airspeed/Mach. The airspeed/Mach reference is also synchronized to the aircraft’s current airspeed/Mach when the autopilot is engaged with the active vertical mode in FLC. The airspeed/Mach reference can be manually adjusted using the SPEED knob on the FCP, and is displayed in cyan next to the FLC mode annunciation. Automatic transition between IAS and Mach airspeed reference occurs at 33,600 feet MSL. Mach reference automatically selects when the airplane climbs through 33,600 feet MSL, and IAS reference automatically selects when the airplane descends through 33,600 feet MSL. Bombardier Challenger 605 - Automatic Flight Control System Page 39 FLIGHT DIRECTORS (CONT'D) FLC mode is cleared by: • Pushing the FLC button; • Selecting another vertical mode, or • Capturing an armed vertical mode. FLC Overspeed Protection Mode The FCCs incorporate an overspeed protection mode to limit the aircraft indicated airspeed/Mach from exceeding VMO/MMO. Overspeed protection is applied with the flight directors off, and in any active vertical flight director mode except GS, ALTS or ALT. FLC overspeed mode is activated automatically in the event of an overspeed condition; when the airspeed is 10 KIAS above VMO, or Mach number is 0.015 M above MMO. When FLC overspeed mode is active, a flashing yellow FLC annunciation is displayed in the active vertical field of the FMA. The flight directors, if not in view, automatically appear, and provide pitch commands to reduce airspeed 5 knots below VMO, or 0.02 Mach below MMO. FLC overspeed mode is automatically cleared when this airspeed/Mach reference is reached. The vertical mode will revert to FLC mode when the FLC overspeed mode is cleared. NOTE FLC overspeed mode cannot be cleared by pressing the FLC button. As well, the flight directors cannot be selected off during FLC overspeed mode operation. Flight Level Change Mode Figure 04−10−33 Bombardier Challenger 605 - Automatic Flight Control System Page 40