37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Attributes | |
ACN | 878291 |
Time | |
Date | 201003 |
Place | |
Locale Reference | ZZZ.Airport |
State Reference | US |
Aircraft 1 | |
Make Model Name | MD-80 Series (DC-9-80) Undifferentiated or Other Model |
Operating Under FAR Part | Part 121 |
Flight Phase | Initial Climb |
Route In Use | SID ZZZ |
Flight Plan | IFR |
Component | |
Aircraft Component | Autoflight System |
Events | |
Anomaly | Deviation - Procedural Published Material / Policy |
Narrative:
A recent change has the MD80 crews engaging the autopilot at 500 ft AGL. The end result of this change has the aircraft pitching up to match the command speed of V2+10; sometimes with pitch attitudes reported in excess of twenty degrees airplane nose up. At these extreme pitch altitudes; the potential for catastrophe should an engine fail is enormous. This aircraft is flown with tabs instead of direct linkage to the control surfaces; and as such there is a delay between control wheel input and control effectiveness. Should an engine fail at; for example 900 ft AGL with a pitch attitude in excess of twenty degrees and an airspeed of V2+10; the airplane will roll toward the dead engine and the crew may not be able to recover! The argument that this procedure has been successfully flown in the simulator is not valid. When a crew is in the simulator they are geared toward experiencing emergency conditions and situations and such are spring loaded to handling extreme problems. On the line; when a pilot is flying a typical three leg/two leg/five leg three day trip it is simply not possible nor reasonable for the typical pilot to be in the same 'simulator' mindset 24/7. The pilot is dealing with aircraft swaps; mechanical and MEL problems; air traffic control delays and the usual time pressures and is simply trying to make it through the trip. If on leg four of day three the crew blows an engine while performing the RNAV out of a major airport they are tired and strung out from everything they've had to deal with on the trip. At V2+10 at 900 ft AGL; they may not catch the engine failure fast enough to prevent the loss of the aircraft. With this procedure there is no margin of safety. Furthermore; the tolerances on RNAV departures are too tight to be realistic. Pilots are human; mistakes are made and crosswinds exacerbate those mistakes. In situations such as this where there is no margin for error -- none; it is not reasonable to expect a crew to put their licenses at risk. When crews are being told to maintain course within the 1/3 of a dot of CDI deflection with the threat of violation should that CDI exceed 1/3 of a dot; they are not looking outside for traffic or maintaining good situational awareness -- they're concentrating solely on the CDI; and that is not safe. The solution is easy. One airport's RNAV procedure is to receive an initial vector from the local controller prior to takeoff and after the flight is established on a proper course; the departure controller issues a clearance direct to a fix on the RNAV departure. If all airports to enact the same procedure the problems would cease immediately. Until such time as this fix is established; the procedure of flying RNAV's with the extreme lack of tolerance using the autopilot is simply not safe.
Original NASA ASRS Text
Title: An MD80 pilot reported that a Company procedure of engaging the autopilot at 500' is a safety issue because of the aircraft's high pitch; slow airspeed; and the possibility of crew error should an engine fail in that configuration.
Narrative: A recent change has the MD80 crews engaging the autopilot at 500 FT AGL. The end result of this change has the aircraft pitching up to match the command speed of V2+10; sometimes with pitch attitudes reported in excess of twenty degrees airplane nose up. At these extreme pitch altitudes; the potential for catastrophe should an engine fail is enormous. This aircraft is flown with tabs instead of direct linkage to the control surfaces; and as such there is a delay between control wheel input and control effectiveness. Should an engine fail at; for example 900 FT AGL with a pitch attitude in excess of twenty degrees and an airspeed of V2+10; the airplane will roll toward the dead engine and the crew may not be able to recover! The argument that this procedure has been successfully flown in the simulator is not valid. When a crew is in the simulator they are geared toward experiencing emergency conditions and situations and such are spring loaded to handling extreme problems. On the line; when a pilot is flying a typical three leg/two leg/five leg three day trip it is simply not possible nor reasonable for the typical pilot to be in the same 'simulator' mindset 24/7. The pilot is dealing with aircraft swaps; mechanical and MEL problems; air traffic control delays and the usual time pressures and is simply trying to make it through the trip. If on leg four of day three the crew blows an engine while performing the RNAV out of a major airport they are tired and strung out from everything they've had to deal with on the trip. At V2+10 at 900 FT AGL; they may not catch the engine failure fast enough to prevent the loss of the aircraft. With this procedure there is no margin of safety. Furthermore; the tolerances on RNAV departures are too tight to be realistic. Pilots are human; mistakes are made and crosswinds exacerbate those mistakes. In situations such as this where there is no margin for error -- NONE; it is not reasonable to expect a crew to put their licenses at risk. When crews are being told to maintain course within the 1/3 of a dot of CDI deflection with the threat of violation should that CDI exceed 1/3 of a dot; they are not looking outside for traffic or maintaining good situational awareness -- they're concentrating solely on the CDI; and THAT IS NOT SAFE. The solution is EASY. One airport's RNAV procedure is to receive an initial vector from the local controller prior to takeoff and after the flight is established on a proper course; the departure controller issues a clearance direct to a fix on the RNAV departure. If all airports to enact the same procedure the problems would cease immediately. Until such time as this fix is established; the procedure of flying RNAV's with the extreme lack of tolerance using the autopilot is simply not safe.
Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.