Empty Promises on a Needed Safety Improvement

The “letter wars” between the National Transportation Safety Board (NTSB) and the Federal Aviation Administration (FAA) are a priceless mother lode of illogic. The NTSB can issue a perfectly logical and straightforward safety recommendation, the FAA can provide a non-answer, and the NTSB can characterize the answer as responsive to its recommendation.

I would like someone, anyone, to tell me how this advances aviation safety.

The latest discouraging example comes with Brazil’s December 2008 report of investigation into the 2006 mid-air collision high over the Amazon between a GOL B737 with 154 people aboard (all of whom died) and an Embraer-135 Legacy business jet with seven aboard (all of whom survived without a scratch).

There are numerous reasons why two airplanes were on the same airway at 37,000 feet, flying in opposite directions, but one thing is clear: the TCAS (Traffic Alert Collision Avoidance System) on the EMB-135 Legacy was inoperative at the time, and neither the ground controller nor the pilots of the Embraer were aware of this fatal anomaly. (See story in Aviation Safety & Security Digest, ‘Complacency & Computer Perversity Lead to Brazilian Mid-air Collision’)

Since modern navigation systems provide for accuracy right down the centerline of an aerial highway, a mid-air collision was highly likely with the last-ditch TCAS in the EMB-135 Legacy inoperative, unable to communicate either with the ground radar (thereby providing an accurate altitude for the EMB-135), or with the GOL B737 (thereby providing an escape maneuver for the two jets, approaching at a combined rate of 1,000 mph, one to climb and the other to descend).

The Brazilian report calls for an improved man-machine interface in the cockpit to prevent “inadvertent actions” such as turning off TCAS, and in a footnote references an NTSB recommendation to the FAA.

It’s worth spending a few moments exploring the sorry history of that recommendation.

In its 6-page letter of May 2007 to the FAA, the NTSB noted:

“Federal Aviation Regulations require that all aircraft equipped with TCAS must have the TCAS unit operational, thereby helping to ensure that the safety benefits of these systems provide in mitigating the risk of midair collision are realized. However, it is also imperative that when a failure of these systems occurs that flight crew attention is rapidly captured so that actions can be taken to mitigate this failure.”

The NTSB then urged the FAA to:

“Require, for all aircraft required to have a traffic alert and collision avoidance system installed and for existing and future system designs, that the airborne loss of collision avoidance system functionality, for any reason, provide an enhanced aural and visual warning requiring pilot acknowledgment. (A-07-35)”

So far, so good. When the TCAS was inadvertently switched off on the EMB-135, a white colored “STANDBY” message illuminated on the primary flight display (PFD). This message might be reasonable on the ground, but it needs to be more attention-getting in the air. A flashing red-colored message and an aural chime would to the trick. The chime would alert pilots to something they should look for on their instrument panel, and the flashing red message would instantly alert them to the nature of the problem.

By the way, the TCAS can be switched off by pressing a single multi-function button twice within 20 seconds. It would seem that this vital system should have a more unique, stand-alone control, but that is a separate issue.


On the EMB-135, the TCAS is controlled by a single multi-function button on the RMU (radio management unit), one of which is located on the captain’s side (left) and the other on the first officer’s side (right), as indicated by the red circles. If the TCAS is switched to Standby/Off, a message in white letters appears on the primary flight display. The NTSB believes all TCAS units require more attention-getting alerting if they are switched off in flight.

Remember what the NTSB recommended: an aural and visual alarm on all TCAS-equipped airplanes, present and future.

Read carefully the FAA response (weasel words underlined for emphasis):

“The Federal Aviation Administration has no objective evidence of problems associated with transponder/traffic alert and collision avoidance systems (TCAS) being inadvertently turned OFF (or to Standby). This type of control panel, which incorporates line select push buttons, is installed in various locations in other aircraft types. In these other installation locations, we believe that the design of the panel provides adequate protection against inadvertent operation of the line select button that controls the transponder ON/Standby mode … the FAA believes the proper course of action is to investigate fully the installation on the [EMB-135] Legacy aircraft and to require corrective action as appropriate.

“The FAA will also review installations on other aircraft that use this particular control panel to determine the need for corrective action. If our review uncovers an installation where the transponder/TCAS controls have the potential for inadvertent operation, we will consider the need for enhanced warning. At this time, based on the interim findings of this accident, the FAA does not see the need to raise the level of alerting on all TCAS-equipped aircraft.

“In addition, the FAA will evaluate general flight deck alerting philosophy of planes required to carry TCAS equipment and assess if it needs to be adjusted to ensure pilots have adequate notification of abnormal or unanticipated TCAS functionality. As part of this evaluation, we will evaluate the need for fleet-wide retrofit of enhanced annunciation of TCAS failures …”

Let me emphasize key phrases:

“If our review …”

“potential for inadvertent operation …”

“we will consider …”

This is far short of an expression like:

“We consider your recommendation valid for all TCAS equipped aircraft and will take action within 12 months to require aural and visual alerting in the event that the TCAS is not functioning when the aircraft is airborne.”

That’s a positive response, not the bafflegarb the FAA served up.

The NTSB recommendation basically said that losing TCAS in the air merits a chime and a line in the EICAS (Engine Indication and Crew Alerting System) message list. It’s worth as much attention as losing a hydraulic system, one would think.

There is no indication of when the FAA will conduct its review of “general flight deck alerting philosophy” and no promise of any action, for any airplane, including the EMB-135 Legacy.

Empty words; empty promises. The rhetoric sounds good, but falls well short of any commitment. In fact, the FAA regards the TCAS control panel installation on the EMB-135 as unique and action across the fleet of all models of aircraft is probably not required. In other words, the FAA disagrees with the NTSB recommendation.

Yet in the face of this evident brush-off, the NTSB strangely characterized the FAA answer as “Open – Acceptable Response.” I suppose the recommendation is “Open” because the NTSB is awaiting the results of the FAA study of “general flight deck alerting philosophy.” Don’t hold your breath.