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Precision Vertical Navigation on the MD11/MD10 :

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Presentation on theme: "Precision Vertical Navigation on the MD11/MD10 :"— Presentation transcript:

1 Precision Vertical Navigation on the MD11/MD10 :
PROFILE V/S • PROF • IDLE • HOLD Capt. Brad Alberts MD11 Captain

2 Disclaimer This slide show is an attempt to more adequately explain precision vertical navigation on the MD11/MD10, know as PROFILE. It is a work-in-progress at this point in time. Please confirm all information herein against CFM or other official FedEx/Boeing/Honeywell documents. Make the aircraft do what you want it to do and fly safe! I can be reached for questions at: Jan 2008

3 CFIT: Controlled Flight Into Terrain
Leading cause of hull loss around the planet Most preventable through solid procedures Requires all levels of protection to breakdown Precision Vertical Navigation Systems (PROF) can assist in preventing it if used properly in the approach environment! Jan 2008

4 Review: Flying Tiger Flt 66 Arrival KUL
Non-Precision/Automated Non-VNAV aircraft ATC Cleared descent to 2,400’ “Descend two four zero zero” Crew heard, read-back & entered 400’! Descend to “four zero zero” Min segment altitude 2,400’ Aircraft descended and crashed into side of mountain descending to 400’ Jan 2008

5 CFIT Levels of Prevention
Crew Situational Awareness (S/A) Where are we & what’s below us? PROFILE/VNAV (V/S • PROF • IDLE • HOLD) Using Vertical Navigation (VNAV or PROF) ATC Terrain Warning System Most 1st World Countries only! EGPWS Activation & Escape Bottom layer of protection Jan 2008

6 Definitions Calculated Vertical Descent Path (CVDP):
The FMS calculated descent path that optimizes speed, fuel & DOC saving with path angle stabilization in compliance with MCDU distance, constraints & winds. Touching PROF enters autoflight into management of this profile. It is calculated without regard to how descent is actually flown. Top of Descent Point (TOD): FMS calculated Top of Descent point based on mileage (magenta line), speed & altitude constraints &winds aloft entry in PERF page PROF: FMA display when aircraft is operating ON the CVDP path (when profile management is activated after touching the PROF tile) V/S: FMA display when aircraft is below the CVDP or the pilot has started descent prior to calculated TOD using Vertical Speed (V/S) followed by pushing PROF IDLE: FMA display when aircraft is above the CVDP HOLD: FMA display when aircraft is in level altitude capture mode Jan 2008

7 PROF System Architecture
Series of “IF > THEN” logic-flow statements Next “thing to do” is conditional on something occurring and triggering it New altitude, airspeed, config change Change limited to programmed options Limited pilot knowledge of how automation works leads to “the airplane is all up!” & using LVL CHG instead when PROF doesn't go as anticipated due to limited knowledge Jan 2008

8 PROF Design Considerations
FAA Violations: 93 to 1 93 Altitude violations for each Speed violation Aircraft alerts you to altitude errors as follows: Altitude errors are annunciated on MCDU scratch pad Arrows on ND also display altitude reached past required fix High & long information displayed on the PERF page System designed to comply with the crossing altitude restriction before speed compliance System ‘advises’ pilot of inability to maintain speed Flashing FMA above at selected Speed +10 KIAS ADD DRAG advisory in ND Jan 2008

9 Design of PROF: “IF>THEN” Conditional Statements • NADP 1
Push PROF to begin sequence: 400’ AGL- PROF PRE-PROGRAMMED TO: Speed MaintainsV2-V2+10 Flex/Max PWR A different logic-flow tree PRE-PROGRAMMED TO: At Anytime: CONDITION TO MEET: Confirm E/O? Speed MaintainsV2-V2+10 Flex/Max PWR 1,000’ AGL CONDITION TO MEET: Reaching EO Accel Alt Climb Power Accelerate to 250 KIAS 3,000’ AGL Reaching FCP Speed-250 Accel KIAS VFR & VSR prompts Climb to FCP Altitude 10,000’ MSL Reaching FCP Altitude Accel to 330 KIAS/.84 Await further pilot inputs Jan 2008

10 Unintended Consequences of Level Change & V/S (Non-PROF/White FMA Indication)
Dive & Drive mentality of the non VNAV aircraft Thinking that PROF “does not work” Descends to FCP Altitude or hits the ground… whichever come FIRST! FMA Indication t THRUST 250 NAV 1 IDLE CLAMP 400’ Jan 2008

11 Creating Accurate TOD Point (Top of Descent)
Loading accurate Magenta Line miles Look for un-needed fixes in STAR’s • SID’s • IAP’s Use local knowledge of ATC procedures (FOM Compliance) Loading SID/STAR Constraints Crossing altitudes & speed limits Loading TOD & Airport Winds/Temp PERF pg 2: DESCENT FORECAST Anti-Ice does nothing in MD10 No FADEC to increase N1 when Anti-ice is ON like the MD11 Jan 2008

12 Using PROF in Descent Only three possible relationships relative to the calculated profile (CVDP): Above profile angle Profile FMA: IDLE Past TOD point-IDLE power (Speed on Pitch) when lower altitude entered in FCP On profile angle Profile FMA: PROF When started down at TOD point-power is THRUST (Speed on Thrust) Below profile angle Profile FMA: V/S Descend prior to TOD requires pilot applied V/S-power is THRUST (Speed on Thrust) Jan 2008

13 Vertical Deviation Indicator (VDI) in relation to CDA Profile angle
Diamond represents aircraft location relative to the Profile/ CVDA path Aircraft is Below profile (low) Autothrottles: Speed on Thrust FMA: V/S 1,000’ Aircraft is On Profile Autothrottles: Speed on Thrust FMA: PROF Mid-point bar indicates center of CVDA path- “On Profile” Aircraft is Above Profile (high) Autothrottles: Speed on Pitch FMA: IDLE 100’ Jan 2008

14 Starting the Descent in relationship to the Top of Descent point
If started PRIOR to calculated TOD: enter new alt in FCP- Select an appropriate V/S then press PROF or Enter the newly assigned altitude in MCDU INIT page - 750’fpm Magenta V/S is “PROF Armed” condition-if CVDA profile is re-intercepted it reverts to & captures the profile: PROF If started AT calculated TOD Descend in PROF ATC offers “Pilot discretion” descent If started PAST calculated TOD Dial in new altitude in FCP Aircraft will descend in IDLE Magenta IDLE in “PROF Armed” condition-if calculated profile re-intercepted it captures the profile: PROF VDI Jan 2008

15 Using the VDI to determine CVDP location • A/T power
FL330 or Calculated descent profile (CDA) IDLE 8,000’ V/S *Requires PROF be touched after V/S initiated PROF VDI 10,000’ or 3,000’ Jan 2008 Autothrottles: IDLE=idle PROF=thrust V/S=thrust

16 How the MD11 tells you it knows it’s above profile…
The VDI shows diamond below center mark Intercept “Icons” start to appear on magenta line PERF page shows how high & long FLTPL page shows “* DECEL” in 1R When you see these signs & enter a lower altitude in PROFILE the throttles can only go to one setting: IDLE    ECON DES PATH ERROR PRED TO 5320HI 12LONG ECON UTC DIST TOD IDLE FL330 VDI Intercept with 2/3 Speed Brakes (white) Where aircraft will level at new altitude Re-intercept on it’s own-clean wing! (magenta) 10,000’ Jan 2008

17 What causes an ALT ERROR AT…?
Aircraft above the CVDP Alert always shown in the scratch pad. When the magenta intercept ball goes past the upcoming constraint the ALT ERROR alert occurs in the scratch pad. If the white IP is still prior to the constraint speed brakes could salvage the crossing restriction. When the magenta IP move back prior to the constraint the error message will disappear. Jan 2008

18 Where will the aircraft descend to in PROF?
Whichever is higher: MCDU: Line 2 R–LARGE font altitude (Here HAYDN at 4,000’) SMALL font altitudes & 1R are never honored   FMS calculated or actual crossing altitudes                  FCP Altitude (where would it descend now if in PROF?)    400 V/S T-P HAYDN MCGEE 36L Jan 2008

19 Advantages of flying the PROF Profile/CDA (vs
Advantages of flying the PROF Profile/CDA (vs. dive & drive-LVL CHG/ IDLE CLAMP) Less fuel used Less VFR traffic conflicts Less noise for our neighbors Reduced bird strike chances Operating on a stabilized descent Farther away from CFIT! Jan 2008

20 Alternate Way to Utilize Level Change (& V/S for that matter!)
If Level Change is necessary – pull Level Change Verify VDI diamond is not in the PROF capture zone Touch PROF – Altitude FMA is now IDLE (magenta) Aircraft now has big font MCDU altitude protection t THRUST NAV 1 IDLE ’ Jan 2008

21 V/S to IDLE Issue Scenario: you initiate a V/S descent and hit PROF. The FMA changes to IDLE ‘unexpectedly’ It may be a function of the margin between the FMS derived cruise speed vs. high-speed foot V/S is Speed on Thrust. If the magenta ball is too close to high-speed foot there is insufficient speed margin to control a speed-on-thrust command Aircraft defaults to IDLE as a result. This has been seen less on the MD11 due to higher margins between the magenta ball and high-speed foot. Treat Profile software like dealing with Crew Scheduling: Trust but Verify! MD10-10 MD11 Jan 2008

22 Technique for Complying with an Early Descent to a Lower Intermediate Cruise Altitude
Scenario: you are cleared to descend from FL360 to FL320 prior to TOD then Pilot's Discretion to FL240: Enter FL320 in the FCP (aircraft remains level FL360 due to fact that TOD is some miles ahead of aircraft) Select INIT page on MCDU and enter 320 in line 5L as new cruise altitude Aircraft will then begin a descent in magenta V/S at 750 fpm until reaching FL320 and will capture/HOLD Leveling at FL320 (Magenta HOLD on the FMA) select FL240 in FCP (do not change INIT page). Aircraft will stay at FL320 until newly calculated TOD then start down to FL240 on Profile Jan 2008

23    Arrival Technique Aircraft on a 090° heading JSICA/180°
Approaching this side of the airport: use DIRECT/INBD COURSE (1R in DIRECT TO page). NOTE: being on magenta line not required for accurate profile information NOTE: Wait until rolling out of turn before executing 1R-magenta line is drawn on ground track, not heading Aircraft on a 090° heading Approaching from this area: Go DIRECT to HAYDN /inbound course – 270° and a magenta line (for PROF purposes) mimics a downwind-to-base pattern JSICA/180° SQIDD 36L < 270° JSICA JSICA/270° SQIDD/270° Aircraft on a 300° heading Aircraft on a 330° heading Jan 2008 Jan 2008

24 PROFILE Misc. Issues When at an altitude that is many miles from the next FP point (30 mile final in to MEM) and ATC gives a clearance to descent, this system does not manage very low rate–of-descent vertical speeds well. Use V/S or Level Change to get the VDI diamond out of the PROF capture zone (2-3 diamond heights from center) then select PROF for CFIT protection. Comply with the AIM recommended 500 fpm ROD or ATC request. The last appr fix (usually the FAF) is a big font altitude. If the G/S capture/Land does not capture prior to approx 100’ above that fix’s altitude, the aircraft will go into altitude hold and consequently go above glideslope. Jan 2008

25 Instances When PROF Will Not Work
Switching to HOLD Mode prior to entering a holding fix Within :03 mins of entering holding the aircraft will stop operating in PROF and switch to HOLDING mode Greater than ~150nm from destination (full descent buffer memory issue) If the aircraft is greater than this distance from destination a PROF decent will not be honored as the memory available to manage PROF are limited– ie: coast-in after Atlantic crossing enroute to CDG Jan 2008

26 The Bottom Line: Use PROF whenever possible/appropriate in the terminal environment as another tool to prevent CFIT Make the aircraft complies with ATC instructions: “fly the aircraft” Lower automation level whenever ambiguity arises as to what “HAL” is doing Use the highest level appropriate to conditions and pilot knowledge Jan 2008

27 Operating in PROFILE V/S • PROF • IDLE
Your key to added CFIT protection in the approach environment Safe • Legal • Professional Jan 2008

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