NTSB · Safety Recommendation
Safety Recommendation A-03-054
Recommendation
TO THE FEDERAL AVIATION ADMINISTRATION: If the panel requested in Safety Recommendation A-03-53 determines that a requirement for the installation of low-airspeed alert systems in airplanes engaged in commercial operations under 14 Code of Federal Regulations Parts 121 and 135 is feasible, establish requirements for low-airspeed alert systems, based on the findings of this panel. (Superseded by A-10-12)
Safety Issue and Context
On October 25, 2002, about 1022 central daylight time, a Raytheon (Beechcraft) King Air A100, N41BE, operated by Aviation Charter, Inc., crashed while the flight crew was attempting to execute the VOR approach to runway 27 at Eveleth-Virginia Municipal Airport, Eveleth, Minnesota. The crash site was located about 1.8 nautical miles southeast of the approach end of runway 27. The two pilots and six passengers were killed, and the airplane was destroyed by impact forces and a postcrash fire. The airplane was being operated under the provisions of 14 Code of Federal Regulations (CFR) Part 135 as an on-demand passenger charter flight.
Instrument meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan.
Response History
February 23, 2010 · NTSB Correspondence · FAA
From the safety recommendation letter to the Federal Aviation Administration written in response to the 2/12/2009 accident of a DHC-8-400 (Q400), operated by Colgan Air as Continential Connection flight 3407, in Clarence Center, New York: During the almost 6 years since the NTSB issued Safety Recommendations A 03 53 and 54, (which were reiterated in July 2006 after another event involving decreasing airspeed and loss of control), accidents and incidents involving a lack of flight crew awareness of decreasing airspeed have continued, indicating that existing stall warnings are not a reliable method for preventing inadvertent hazardous low-speed conditions.
The NTSB notes that human factors concerns associated with a low-airspeed alert do not require more than 6 years of study for a solution to be implemented. The NTSB notes that several other airplanes certificated under 14 CFR Part 25, including the Boeing 747-400 and 777, provide pilots with an amber band on the airspeed display above the low-speed cue. This amber band typically represents the airspeed between the stall warning speed and the minimum maneuvering speed. Operations are not normally conducted with airspeeds in the amber band, which, in effect, provides pilots with a visual indication of a developing low speed condition before the onset of the stall warning.
AC 25-11A, Electronic Flight Displays, discusses the visual design of low-speed awareness cues and states, the preferred colors to be used are amber or yellow to indicate that the airspeed has decreased below a reference speed that provides adequate maneuver margin, changing to red at the stall warning speed. The speeds at which the low speed awareness bands should start should be chosen as appropriate to the airplane configuration and operational flight regime. For example, low speed awareness cues for approach and landing should be shown starting at Vref with a tolerance of +0 and -5 knots.
The NTSB concludes that the Q400 airspeed indicator lacked low-speed awareness features, such as an amber band above the low-speed cue or airspeed indications that changed to amber as speed decrease toward the low-speed cue, which would have facilitated the flight crew’s detection of the developing low-speed situation.
Therefore, the NTSB recommends that the FAA require that airspeed indicator display systems on all aircraft certified under