Saturday, December 01, 2007

FAA History Lesson -- December 1

From the FAA Historical Chronology, 1926-1996...

”Dec 1, 1974: Approaching Dulles International Airport under conditions of poor visibility, a Trans World Airlines Boeing 727 descended too soon and crashed into a mountain near Berryville, Va., killing all 92 persons aboard.

Unfamiliar with terrain to the immediate west of Dulles, the TWA captain interpreted a controller's "cleared for approach" instruction to mean that he could descend to the final approach altitude of 1,800 feet immediately, although his chart indicated mountain peaks and a prescribed minimum altitude of 3,400 feet. The controller had assumed the pilot knew he was not to descend to 1,800 feet until he had cleared the mountains. Soon after the accident, FAA took steps to clarify pilot responsibilities for maintaining safe altitude by issuing a notice, followed by a regulatory amendment. This new rule explicitly required that in-bound pilots maintain their assigned altitude until they were given a new one or became established on a published route. FAA also issued additional guidance intended to ensure that controllers informed radar arrivals of any applicable altitude restrictions at the time that they issued an approach clearance. (See Jan 1, 1976.)

With FAA still under scrutiny for its handling of the DC-10 cargo door problem (see Mar 3, 1974), the TWA crash added to intense criticism of the agency (see Dec 27, 1974). The accident underscored the need for a cockpit device to alert pilots if they strayed too close to terrain, and FAA speeded work on a proposed rule to make a terrain warning system mandatory (see Dec 24, 1974). Other FAA actions in the wake of the TWA crash included the appointment of a Special Air Safety Advisory Group, composed of six retired airline captains, which submitted a variety of safety recommendations on Jul 30, 1975. Meanwhile, DOT established a task force on FAA’s safety mission (see Jan 28, 1975). “

You could write an entire book about this accident. F. Lee Bailey did. Cleared for the Approach -- In Defense of Flying. The book also has a lot about PATCO in it. Mr. Bailey was one of the first officers of PATCO. And while you’re busy saying “I didn’t know that”, you might as well Google PATCO + Johnny Carson, Arthur Godfrey, Susan Oliver and Arnold Palmer.

Getting back on track, this is one of the major accidents that had a real impact on air traffic control. The most obvious consequence to controllers is the requirement to issue an altitude to maintain until established on a published segment of the approach.

Section 8. Approach Clearance Procedures


b. For aircraft operating on unpublished routes, issue the approach clearance only after the aircraft is: (See FIG 4-8-1.)

1. Established on a segment of a published route or instrument approach procedure.

2. Assigned an altitude to maintain until the aircraft is established on a segment of a published route or instrument approach procedure.


I’ll use this opportunity to push one of my pet theories. And as always (it seems), it’s an unpopular one. I believe this accident was the tip of the iceberg -- an iceberg that I’ll call “direct-itis.” I don’t think I can lay claim to the term. I think I got it from Wally Roberts. You may not have heard of Wally and you may not know what TERPS is but Wally is the man.

There was a time when airplanes flying in instrument conditions stayed on airways. Airways always had Minimum Enroute Altitudes (MEA) posted on them. Think of it in three dimensions. Airways didn’t just provide lateral guidance -- across the ground -- they provided vertical guidance to keep you above the ground -- above the terrain.

With the advent of radar it started getting easier and easier to get aircraft off those “restrictive” airways. When you’re thinking of getting to your destination, anything that isn’t a straight line makes “restrictive” sound bad. When you think about flying through a mountain pass to an airport, “restrictive” suddenly sounds like a good thing.

From one of my favorite research sites:

”The issuance of the approach clearance when the flight was 44 miles from the airport on an unpublished route without clearly defined minimum altitudes.”

(Emphasis added)

If you’re on an airway -- a published route -- and the MEA says 5,000, you know what is safe. If you’re on an unpublished route there isn’t an MEA. The Minimum IFR Altitude (MIA) can change by the second, which is one of the reasons they’re unpublished (for pilots.) It’s as simple as Known vs. Unknown.

The #1 reason pilots want to go direct is simply to save time. People who fly in airplanes tend to be in a rush. It feeds the mentality that direct is always better, hence the term “direct-itis.” It helped kill all the people aboard TWA514, all the people aboard AAL965 and it’s probably not done yet.

The common wisdom that you should be able to fly direct in the wild blue yonder remains mostly unchallenged -- and everyone is aware of the dangers terrain presents once they’ve begun an instrument approach. However, there’s a huge gap in the transition between the two -- between “random” and “precision”, between published and unpublished -- that many refuse to face. How do you transition from random to “un-random” ? Once you answer it for approaches, find the answer for departures. Where do you transition from “un-random” to random ?

A review of Safety Board accident data revealed that, on March 16, 1991, at 0143 Pacific standard time, a Hawker Siddeley DH125-1A/522 transport-category turbojet airplane crashed into mountainous terrain about 8 nm northeast of SDM, killing 10 people. The Hawker accident site was located within 1.5 miles of the Learjet accident site. The Hawker accident site was at the 3,300-foot level of Otay Mountain and about 172 feet below the mountain’s top.

...” The captain stated that he wanted to depart from runway 8 to avoid flying over the city of San Diego. He also stated that a runway 8 departure would place the flight on a heading straight toward ABQ, and the copilot agreed with this statement. Neither the captain nor the copilot mentioned the mountainous terrain to the east and northeast as a consideration in deciding which runway to use for departure.”

(Emphasis added)

“Directitis” got them too.

Don Brown
December 1, 2007

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