Hudson River Mid-Air Collision

by philg

Wednesday, August 19, 2009 at 11:33 AM EDT

A lot of folks have been asking me about the Hudson River mid-air collision on Saturday, including some WCVB TV reporters (clip). The best information that I’ve been able to find is a New York Times graphic showing the path of the accident airplane.

Some context may be obtained by visiting http://skyvector.com/ and choosing the New York Terminal Area Chart (currently the default on the site). Most of the airspace around New York City is Class B, the most protected airspace in the U.S. In Class B airspace every aircraft must be talking to air traffic control, identified on radar, and positively separated from other aircraft. This is how we fly our sightseeing tours over downtown Boston, which falls within Logan Airport’s Class B. Due to the historically large numbers of sightseeing airplanes and helicopters zipping up and down the Hudson River, the FAA decades ago carved out a “VFR corridor” to allow aircraft flying over the river at or below 1100′ above sea level to fly without talking to a controller. In fact, an airplane could fly through the corridor without being equipped with a radio.

The FAA does not explain how pilots should use the corridor. Common sense and convention suggests the following:

• keep to the right
• fly low (700′ or below) if you’re a helicopter and not subject to the “at least 500′ above any vessel, person, or structure” rule
• fly high-ish (900′ to 1100′) if you’re an airplane
• tune your radio to the published common traffic advisory frequency (CTAF) and periodically broadcast position reports

Teterboro Airport is more or less abeam mid-town Manhattan. An airplane departing Teterboro could enter the corridor almost anywhere. Whenever I have done it, however, it has made sense to me to first head north over the land and still within Teterboro’s controlled airspace. I enter the corridor at the George Washington Bridge. The tour helicopters generally don’t come that far north. I switch to CTAF and say “Hudson River Traffic, Cirrus Seven Whiskey Tango at the George Washington Bridge southbound 900″. The next call is abeam Central Park. Even at 110 knots I have a couple of minutes in which to let the downtown mob know that I’m coming and to listen for airplanes and helicopters farther downtown.

With this accident, it appears that the helicopter may have climbed higher than typical, perhaps close to the 1100′ ceiling of the corridor. More problematic was the airplane pilot’s decision to enter the busy corridor on a busy weekend day at its busiest spot, more or less abeam the W. 30th St. heliport. He would have been required to be talking to Teterboro or Newark Tower until the very moment that he was over the river (though there is some suggestion in today’s New York Times that he was handed off from TEB to EWR and did not check in with Newark). He thus denied himself the chance to spend a minute or two broadcasting his progress down the river and listening for the helicopter who would surely have reported lifting from W. 30th. Had the airplane pilot spent an additional four minutes of flight time (two minutes north to the G.W. Bridge and then two minutes south down the river) the accident probably could have been avoided. This is not to criticize the pilot. The Teterboro controllers are not famous for being friendly or flexible. It is possible that the airplane pilot asked to fly north first and was denied due to traffic (TEB is one of the nation’s busiest airports).

Should anything be done? It might be helpful if the FAA published an official guide to using the Hudson River corridor codifying the rules listed above and adding one new rule: airplanes should enter the corridor at the G.W. Bridge or farther north and/or from the Verrazano Bridge or farther south. Controllers at nearby airports should be trained to encourage pilots to follow those entry procedures. Except for seaplanes or helicopters lifting from the river itself, nobody should join the party right in the middle (a seaplane or helicopter taking off from inside the corridor would likely have been monitoring the CTAF for at least a couple of minutes).

About a month ago, I had to go to Washington, D.C. to be deposed as an expert witness (albeit not as an aviation expert witness). As the weather was fairly nice, I elected to fly a Cirrus SR20 down there and stopped at Teterboro for lunch with a cousin. I brought my nephew along for the trip and decided to show him New York City from the Hudson corridor. It was the middle of the week rather than a weekend day. We flew north to the G.W. Bridge prior to entering the corridor. We stayed at 900′ and never got close to any other aircraft as far as I know.

More: an interview with me on local TV

This article originally appeared on Philip Greenspun's Weblog.