Ignored Warnings About Warnings

The fatal takeoff crash in August of a Spanair MD-82 unfortunately is the second bookend, as it were, to over 20 years of Federal Aviation Administration (FAA) inaction. I should add here that the National Transportation Safety Board (NTSB) has apparently condoned a non-response to its safety recommendations.

The first bookend occurred August 1987, when a DC-9 crashed on takeoff at Detroit, in part because the Central Aural Warning System (CAWS) failed to warn the flight crew that the airplane was not configured properly for takeoff. The slats and flaps were not deployed, as a result of which the airplane entered a stall, struck a light pole and crashed.

The MD-82 is a direct descendant of the DC-9 design and has many elements in common, including the CAWS and its associated circuitry.

It’s too soon to know whether the CAWS on the Spanair MD-82 did or did not alert the crew to the fact that their flaps and/or slats were not deployed before the ill fated takeoff run. However, there was work on an electrical circuit that controls CAWS functioning before the aircraft left the gate, after it had returned to the ramp for a malfunctioning heating element in the ram air temperature (RAT) sensor. The RAT sensor is on the same circuit breaker that controls the CAWS.

After the 1987 crash at Detroit, the NTSB issued a voluminous report in which, among other things, it recommended the FAA conduct a “directed safety investigation” into circuit breakers that can disable vital operating systems. The NTSB also recommended that a fail light be installed on the overhead panel, to illuminate in the event of a CAWS power loss.

What was the result of those recommendations? Apparently, a perversion of the English language, such that the NTSB classified these two recommendations as CLOSED – ACCEPTABLE ALTERNATE ACTION.

With regard to the “directed safety investigation,” the last input the NTSB received from the FAA on this recommendation was hardly reflective of a sense of urgency or priority. The FAA told the NTSB it was “gathering data from both the airplane and circuit manufacturers to determine what, if any, action should be taken.”

Wait a minute. There shouldn’t have been any doubt about action to be taken: a thorough review of circuit breakers, the systems they were connected to, and corrective action if systems critical to flight safety, like CAWS, were hooked up to the same circuit breaker that controls a non-essential item like the RAT sensor heating element.

Regarding the CAWS fail light, the NTSB said, “While the FAA did not require the recommended modification to the DC-9 CAWS fail light circuit, the Safety Board accepts the actions taken by the FAA.”

What were those actions? Not to install a fail light, but to eliminate nuisance CAWS warnings so pilots wouldn’t be tempted to deactivate the system.

The FAA did not take action on either of the recommendations, yet the NTSB classified the responses as ACCEPTABLE.

By this standard, the FAA doesn’t have to do much, if anything, to satisfy the NTSB. The whole process of the NTSB issuing recommendations and the FAA responding is something of an elaborate minuet. Evidently, generating correspondence – rather than implementing the recommendations – is sufficient to placate the NTSB even when a warning light is not installed and a “directed safety investigation” is not conducted.

The FAA is derelict for tolerating a known design flaw – pulling a circuit breaker for one reason leads to another consequence, the flight-critical CAWS being rendered inoperative. The NTSB is culpable for characterizing the FAA’s inaction as acceptable.