The NTSB on the Hudson River crash

Late last week the National Transportation Safety Board put out a "safety recommendation" letter about preventing accidents in the "VFR Flyway" above the Hudson River. For previous items on the August 8 airplane-helicopter collision that killed nine people, see here, here, here, and here. VFR = "Visual Flight Rules," in which pilots are responsible for their own navigation and for keeping out of other planes' way.

The full NTSB account of the accident will take many months to complete. This interim recommendation, available in PDF here, is interesting in several ways. First, in contrast to some excitable "it's the Wild West up there!" comments by politicians and media figures, it notes that there have been no previous collisions in 30 years of operating under current procedures over the Hudson, and just one reported "near miss" in the past ten years. Thus, "The procedures in use to promote separation between VFR flights appear to have been effective in preventing collisions." [Full quote from this section, with caveat, after the jump.]

Nonetheless, its recommendation for avoiding problems in the future includes something that makes obvious sense: keeping helicopters and airplanes at different altitudes, since helicopters can safely operate much closer to the ground than airplanes can. This recent collision happened at 1,100 feet -- the altitude at which airplanes typically fly through the corridor, since above that they get into controlled "Class B" airspace for New York's three major airports. The airplane was flying level at that altitude; the helicopter climbed to that altitude just before the crash. By the NTSB's recommendations, helicopters would not get that high.

There are other observations about air traffic control procedures to keep a closer eye on traffic. (For the reaction from air traffic controllers' union, see this Washington Post item. More on the merits of this part of the argument later.) Worth checking out.

The NTSB says about the safety record in the Hudson River VFR flyway:

"Recent FAA traffic estimates indicate that over 200 aircraft a day pass through the Hudson River class B exclusion area. The Hudson River class B exclusion area and associated transition procedures have been in use for more than 30 years, and the safety record for operations in the area has been good. The NTSB has no record of previous collisions between aircraft operating in the Hudson River class B exclusion area. A review of the FAA Near-Midair Collision (NMAC) database and the National Aeronautics and Space Administration Aviation Safety Reporting System (ASRS) database revealed 11 reports of NMACs between aircraft in the area since 1990. Only one report was filed in the past 10 years. Although ASRS reporting is voluntary, the number of reports received is very low relative to the number of flight operations through the Hudson River class B exclusion area. The procedures in use to promote separation between VFR flights appear to have been effective in preventing collisions."

The ASRS system mentioned here is run by NASA. It's an innovative and very useful "no fault" reporting system designed to reveal emerging patterns of unsafe operations. Pilots, air traffic controllers, and others involved in aviation send in reports after experiences that caused, or might have caused, problems. Then analysts collate the reports to see if rules or training systems need to be changed.

The innovative part of the system is its strictly anonymous, confession-booth nature. Pilots, controllers, etc are assured that nothing they report via ASRS will ever be used against them in disciplinary procedures (barring admissions of outright criminal intent). Indeed, if a pilot (controller, etc) is at risk of being disciplined, evidence that he immediately filed an ASRS report can mitigate the punishment. As a result, the reports can be amazingly frank, and the monthly summaries are always absorbing to read. The main ASRS page is here; if you have something to get off your chest, the electronic submission site is here; a description of the confidentiality policy is here; and samples of the regular monthly reports are here and here.