AN ACCIDENT OF HISTORY

We regularly ask after the limits of historical inquiry; we agonize over the right combination of psychological, sociological, and technical explanations. We struggle over how to combine the behavior of machines and practices of their users. Imagine, for a moment, that there was a nearly punctiform scientific-technological event that took place in the very recent past for which an historical understanding was so important that the full resources of the American government bore down upon it. Picture further that every private and public word spoken by the principal actors had been recorded, and that their every significant physical movement had been inscribed on tape. Count on the fact that lives were lost or jeopardized in the hundreds, and that thousands of others might be in the not so distant future. Expect that the solvency of some of the largest industries in the United States was on the line through a billion dollars in liability coverage that would ride, to no small extent, on the causal account given in that history. What form, we can ask, would this high-stakes history take? And what might an inquiry into such histories tell us about the project of – and limits to – historical inquiry more generally, as it is directed to the sphere of science and technology?

There are such events and such histories – the unimaginably violent, destructive, and costly crash of a major passenger-carrying airplane. We can ask: What is the concept of history embedded in the accident investigation that begins while crushed aluminum is still smoldering? Beginning with the Civil Aeronautics Act of 1938, the Civil Aeronautics Authority (a portion of which became today’s National Transportation Safety Board) and its successors have been assigned the task of reporting on each accident, determining what happened, producing a “probable cause” and arriving at recommendations to what is now the Federal Aviation Authority (and through them to industry and government) that would avoid repetition. Quite deliberately, the NTSB report conclusions were disqualified from being used in court: the investigative process was designed to have some freedom both from the FAA and from the courts. Since its establishment, the system of inquiry has evolved in ways I will discuss, but over the last half century there are certain elements that remain basically constant. From these consistencies, and from the training program and manuals of investigation, I believe we can understand the guiding historiographical principles that underlie these extraordinary inquiries. What they say – and do not say – can tell us about the broad system of aviation, its interconnectedness and vulnerabilities, but also, perhaps, something larger about the reconstruction of the intertwined human and machinic world as it slips into the past.

3

P Galison and A. Roland (eds.), Atmospheric Flight in the Twentieth Century, 3-43 © 2000 Kluwer Academic Publishers.

There is a wide literature that aims to re-explain aviation accidents. Such efforts are not my interest here. Instead, I want to explore the form of historical explanation realized in the accident reports. In particular, I will focus on a cluster of closely related instabilities, by which I mean unresolvable tensions between competing norms of explanation. Above all, the reports are pulled at one and the same time towards localizing accounts (causal chains that end at particular sites with a critical action) and towards diffusing accounts (causal chains that spread out to human interactions and organizational cultures). Along the way, two other instabilities will emerge: first, a sharp tension between an insistence on the necessity of following protocol and a simultaneous commitment to the necessary exercise of protocol-defying judgment. Second, there is a recurrent strain between a drive to ascribe final causation to human factors and an equally powerful, countervailing drive to assign agency to technological factors. To approach these and related questions, one needs sources beyond the reports alone. And here an old legislative stricture proves of enormous importance: for each case the NTSB investigates, it is possible to see the background documentation, sometimes amounting to many thousands of pages. From this “docket” emerge transcripts of the background material used to assemble the reports themselves: recordings and data from the flight, metallurgical studies, interviews, psychological analyses. But enough preliminaries. Our first narrative begins in Washington, DC, on a cold Wednesday afternoon, January 13, 1982.

The accident report opened its account at Washington National Airport. Snow was falling so hard that, by 1338, the airport had to shut down for 15 minutes of clearing. At 1359, Air Florida Flight 90, a Boeing 737-222 carrying 5 crewmembers and 74 passengers, requested and received their Instrument Flight Rules clearance. Twenty minutes later, a tug began de-icing the left side of the plane, then halted because of further departure delays. With the left side of the aircraft cleared, a relief operator replaced the initial one, and resumed the spraying of heated glycol-water mixture on the right side. By 1510, the relief operator finished with a final coat of glycol, inspected the plane’s engine intakes and landing gear, and found all surfaces clear of snow and ice. Stuck in the snow, the Captain blasted the engines in reverse for about a minute in a vain effort to free the plane from its deepening prison of water, glycol, ice, and snow. With a new tug in place, the ground crew successfully pulled flight 90 out of the gate at 1535. Planes were backed up in holding patterns up and down the East Coast as they waited for landing clearance. Taxiways jammed: flight 90 was seventeenth in line for takeoff.

When accident investigators dissected the water-soaked, fuel-encrusted cockpit voice recorder (cvr), here is what they transcribed from time code 1538:06 forward. We are in the midst of their “after start” checklist. Captain Larry Michael Wheaton, a 34 year-old captain for Air Florida, speaks first on CAM-1. The first officer is Roger Alan Pettit, a 31 year-old ex-fighter pilot for the Air Force; he is on CAM-2.

1538:06 Wheaton/CAM-1 {my insertions in curly brackets} After start

Pettit/CAM-2 Electrical

Wheaton/CAM-1 Generators

Pettit/CAM-2 Pitot heat {heater for the ram air intake that measures airspeed} Wheaton/CAM-1 On Pettit/CAM-2 Anti-ice

Wheaton/CAM-1 {here, because some of the listeners heard “on” and the majority “off’, the tape was sent to FBI Technical Services Division where the word was judged to be “off’.} Off.

Pettit/CAM-2 Air conditioning pressurization Wheaton/CAM-1 Packs on flight Pettit/CAM-2 APU {Auxiliary Power Unit}

Wheaton/CAM-1 Running Pettit/CAM-2 Start levers Wheaton/CAM-1 Idle [ … ]

Preparation for flight includes these and many other checklist items, each conducted in a format in which the first officer Pettit “challenges” captain Wheaton, who then responds. Throughout this routine, however, the severe weather commanded the flightcrew’s attention more than once as they sat on the taxiway. In the reportorial language of the investigators’ descriptive sections, the following excerpt illustrates the flight crew’s continuing concern about the accumulating ice, snow and slush, as they followed close behind another jet:

At 1540:42, the first officer continued to say, “It’s been a while since we’ve been deiced.” At 1546:21, the captain said, “Tell you what, my windshield will be deiced, don’t know about my wings.” The first officer then commented, “well – all we need is the inside of the wings anyway, the wingtips are gonna speed up on eighty anyway, they’ll shuck all that other stuff.” At 1547:32, the captain commented, “(Gonna) get your wing now.” Five seconds later, the first officer asked, “D’they get yours? Did they get your wingtip over ’er’?” The captain replied, “I got a little on mine.” The first officer then said, “A little, this one’s got about a quarter to half an inch on it all the way.”1

Then, just a little later, the report on voice recordings indicates:

At 1548:59, the first officer asked, “See this difference in that left engine and right one?” The captain replied, “Yeah.” The first officer then commented, “I don’t know why that’s different – less it’s hot air going into that right one, that must be it – from his exhaust – it was doing that at the chocks awhile ago but, ah.”

Which instrument exactly the first officer had in mind is not clear; the NTSB (for reasons that will become apparent shortly) later argued that he was attentive to the fact that, despite similar Engine Pressure Ratios (the ratio of pressure at the intake and exhaust of the jet and therefore a primary measure of thrust), there was a difference in the readout of the other engine instruments. These others are the N1 and N2 gauges – displaying the percent of maximum rpm of low and high pressure compressors respectively – , the Exhaust Gas Temperature gauge (EGT), and the fuel flow gauge that reads in pounds per minute. Apparently satisfied with the first officer’s explanation that there was hot air entering the right engine from the preceding plane, and that somehow this was responsible for the left-right discrepancy, the captain and first officer dropped the topic. But ice and snow continued to accumulate on the wings, as was evident from the cockpit voice recorder tape recorded four minutes later. To understand the first officer’s intervention at 1558:12, you need to know that the “bugs” are hand-set indicators on the airspeed gauge; the first corresponds to VI, the “decision speed” above which the plane has enough speed to accelerate safely to flight on one engine and below which the plane can (theoretically) be stopped on the runway. The second speed is VR, rotation speed at which the nosewheel is pulled off the ground, and the third, V2, is the optimal climbout speed during the initial ascent, a speed set by pitching the plane to a pre-set angle (here 18°).

1553:21 Pettit/CAM-2 Boy, this is a losing battle here on trying to deice those things, it (gives) you a false sense of security that’s all that does

Wheaton/CAM-1 That, ah, satisfied the Feds Pettit/CAM-2 Yeah

1558:10 Pettit/CAM-2 EPR all the way two oh four {Engine Pressure Ratio, explained below}

1558:12 Pettit/CAM-2 Indicated airspeed bugs are a thirty-eight, forty, forty four

Wheaton/CAM-1 Set

1558:21 Pettit/CAM-2 Cockpit door

1558:22 Wheaton/CAM-1 Locked

1558:23 Pettit/CAM-2 Takeoff briefing

1558:25 Wheaton/CAM-1 Air Florida standard

1558:26 Pettit/CAM-2 Slushy runway, do you want me to do anything special for this or just go for it?

1558:31 Wheaton/CAM-1 Unless you got anything special you’d like to do 1558:33 Pettit/CAM-2 Unless just takeoff the nose well early like a soft field takeoff or something 1558:37 Pettit/CAM-2 I’ll take the nose wheel off and then we’ll let it fly off

1558:39 Pettit/CAM-2 Be out of three two six, climbing to five, I’ll pull it back to about one point five five supposed to be about one six depending on how scared we are.

1558:45 (Laughter)

As in most flights, the captain and first officer were alternating as “pilot flying”; on this leg the first officer had the airplane. For most purposes, and there are significant exceptions, the two essentially switch roles when the captain is the pilot not flying. In the above remarks, the first officer was verifying that he would treat the slushy runway as one typically does any “soft field” – the control wheel is pulled back to keep weight off the front wheel and as soon as the plane produces enough lift to keep the nosewheel off the runway, it is allowed to do so. His next remark re-stated that the departure plan calls for a heading of 326-degrees magnetic, that their first altitude assignment was for 5,000 feet, and that he expected to throttle back from thrust (EPR) takeoff setting of 2.04 to a climb setting of between 1.55 and 1.6. Takeoff clearance came forty seconds later, with the urgent injunction “no delay.” There was another incoming jet two and a half miles out heading for the same runway. Flight 90’s engines spooled up, and the 737 began its ground roll down runway 36. Note that the curly brackets indicate text I have added to the transcript.

1559:54 {Voice identification unclear} CAM-? Real cold here 1559:55 Pettit/CAM-2 Got ‘em?

1559:56 Wheaton/CAM-1 Real cold 1559:57 Wheaton/CAM-1 Real cold 1559:58 Pettit/CAM-2 God, look at that thing 1600:02 Pettit/CAM-2 That doesn’t seem right does it?

1600:05 Pettit/CAM-2 Ah, that’s not right 1600:07 Pettit/CAM-2 (Well) –

1600:09 Wheaton/CAM-1 Yes it is, there’s eighty {knots indicated airspeed}

1600:10 Pettit/CAM-2 Naw, I don’t think that’s right

1600:19 Pettit/CAM-2 Ah, maybe it is

1600:21 Wheaton/CAM-1 Hundred and twenty

1600:23 Pettit/CAM-2 I don’t know

1600:31 Wheaton/CAM-1 Vee one

1600:33 Wheaton/CAM-1 Easy

1600:37 Wheaton/CAM-1 Vee two

1600:39 CAM (Sound of stickshaker starts and continues to impact)

1600:45 Wheaton/CAM-1 Forward, forward {presumably the plane is over-rotating to too high a pitch attitude}

1600:47 CAM-? Easy

1600:48 Wheaton/CAM-1 We only want five hundred {feet per minute climb}

1600:50 Wheaton/CAM-1 Come on, forward 1600:53 Wheaton/CAM-1 Forward 1600:55 Wheaton/CAM-1 Just barely climb 1600:59 Pettit/CAM-2 (Stalling) we’re (falling)

1601:00 Pettit/CAM-2 Larry we’re going down, Larry 1601:01 Wheaton/CAM-1 I know it 1601:01 ((Sound of impact))

The aircraft struck rush-hour traffic on the Fourteenth Street Bridge, hitting six occupied automobiles and a boom truck, ripping a 41-foot section of the bridge wall along with 97 feet of railings. The tail section pitched up, throwing the cockpit down towards the river. Tom to pieces by the impact, the airplane ripped and buckled, sending seats into each other amidst the collapsing structure. According to pathologists cited in the NTSB report, seventy passengers, among whom were three infants and four crewmembers, were fatally injured; seventeen passengers were incapacitated by the crash and could not escape.2 Four people in vehicles died immediately of impact-induced injuries as cars were spun across the bridge. Only the tail section of the plane remained relatively intact, and from it six people were plunged into the 34-degree ice-covered Potomac. The one surviving flight attendant, her hands immobilized by the cold, managed to chew open a plastic bag containing a flotation device and give it to the most seriously injured passenger. Twenty minutes later, a Parks Department helicopter arrived at the scene and rescued four of the five survivors; a bystander swam out to rescue the fifth.3

Figure 1. Flightpath. Sources: National Transportation Safety Board, Aircraft Accident Report, Air Florida, Inc. Boeing 737-222, N62AF, Collision with 14th Street Bridge, near Washington National Airport Washington, D. C., January 13, 1982, p. 7, figure 1. Hereafter, NTSB-90.