The Swissair Caravelle disaster at Zurich 1963.

[Tee Emm]

Reading that excellent series of books "Air Disaster" by the Australian author Macarthur Job, I came across Volume One, chapter 3 which covered the Swissair Caravelle crash after take off from Zurich on 4 September 1963.

The cause of the acccident was deemed to be overheated brakes which caught fire in the air. The captain had used high power against the brakes while taxiing up and down the runway in an attempt to use engine exhaust to lift the fog. There was no mention in the official accident report that at the time it was a procedure approved by Swissair.

The visibility in fog was so bad that a follow-me vehicle was used to guide the Caravelle to the runway threshold and even then the driver got temporarily lost trying to find the threshold and inadvertently led the aircraft to a taxiway that joined the runway 400 metres from the threshold rather than at the threshold itself. The aircraft then lined up and taxiied at high power against brakes until after covering about 1400 metres, it slowed, turned 180 degrees and taxied slowly right back to the threshold still with engines set to high power. Workmen on the airport in the vicinity of the runway particularly noticed the engine noise was a good deal louder than normal for a taxiing Caravelle.

At the time of the accident a number of foreign pilots were employed on contract by Swissair. A few days ago, one of those pilots now well into his eighties, and who I have known personally since 1976, contacted me to explain what he knew about the accident and to add more information that was not included in the official accident inquiry. He said that immediately after the accident, the page in the relevant flight operations manual that directed the technique of lifting fog with engine exhaust heat, was removed and replaced with a blank page. This technique was nicknamed FIDO after the wartime British method of using pipes along the side of runways that delivered petrol and then ignited to create heat to lift fog.

Several expatriate pilots with Swissair raised strong objections on safety grounds to the FIDO technique of high power against brakes on taxiing, but were over-ruled by the then operations department crewed by Swiss nationals . Yet, another problem affecting brake use had arisen some months earlier when (according to the pilot), Rolls Royce, who manufactured the engine installation in the Caravelle, published a recommendation on engine handling.

I understand the recommendation was to avoid continuous operation between 4500 RPM and 6000 RPM while taxiing. I gather the Caravelle was unable to sustain normal taxi speed at 4500 RPM whereas 6000RPM was too high a power which resulted in a too fast taxi speed. Although Rolls Royce stressed the RPM's were not Limitations - but advice only - Swissair management by Ops manual insertion, directed Caravelle pilots to keep outside those RPM limits and any pilot failing to adhere to those "limits" were called up for tea and bikkies or failed in line checks.

The problem with the 6000RPM top figure was that pilots were forced to use continuous braking to overcome the higher thrust and this resulted in hot brakes while taxiing. In the case of the fatal Caravelle trip, several times the captain nearly ran over the follow-me vehicle while braking against thrust. As my contact stressed, he could not prove any of the statements he made but nevertheless he said it happened.

The reason he gave me for opening up about the circumstances of the Caravelle accident was that at his advancing years and being perhaps one of the last Swissair pilots of that era, he felt the truth should come out since this evidence was never mentioned in the published documents of the accident. He remains convinced that if the ops management at the time had listened to the warnings by the expat pilots of the potential danger of hot brakes that occured not only with taxiing RPM enforced "limitations" but very much exacerbated by the management directed FIDO policy of burning off fog prior to take off with engine power, it is probable the accident would not have happened.

Apologies if the quoted engine RPM figuresmay not be dead accurate but some slack should be allowed for memory limitations of 47 years...

Comments from readers who may be familiar with the Caravelle accident of 4 September 1963 are most welcome and I will pass them along to my old friend.

[diddy1234]

excellent post.

I too have this book and felt something was missing from this article.

[forget]

.... high power against the brakes while taxiing up and down the runway in an attempt to use engine exhaust to lift the fog. There was no mention in the official accident report that at the time it was a procedure approved by Swissair.

I find this 'approval' very hard to believe. Unless the fog dispersal trick had worked every time (highly unlikely) then some aircraft would have returned the gate after taxiing. The brakes would have been under obvious distress and Swissair engineering would have soon stopped the cock-eyed idea. Ready to be proven wrong, but..........

[Centaurus]

Unless the fog dispersal trick had worked every time (highly unlikely)

Not so unlikely in fact. A friend of mine who flew Gnats at CFS on exchange duty from the RAAF, described a similar technique used to disperse snow from the runway at Little Rissington in the Sixties. He ws authorised to taxi the Gnat down the centre of the snow covered runway several times to clear a narrow path using the heat and jet blast from the engine. This enabled flying operations to resume.

Presumably the heat from Gnat jet blast would have affected any fog droplets if they were present? The heat from the two Spey (?) engines of the Caravelle would, I thought, have some effect in lifting the fog a few feet enough for the pilots to see along the runway at minimum RVR. Certainly the official accident report which was published in an ICAO document which I read, stated that the Caravelle involved in the fatal crash, was using this technique to aid fog dispersal

[forget]

.... ICAO document which I read, stated that the Caravelle involved in the fatal crash, was using this technique to aid fog dispersal.

I don't doubt that. I do question the suggestion that the technique was formally approved by Swissair. Very odd.

[Centaurus]

Turns out the advice of fog dispersal was in the company Caravelle European Division FCOM or equivalent in those days but was withdrawn some 18 months before the fatal accident. Apparently Swissair management was unaware of it's inclusion in the FCOM since the responsibility of FCOM procedures was that of the chief pilot. However, on conversion courses to the Caravelle prior to the accident, the brakes versus power method of clearing fog on the runway was discussed. It seems that the captain of the accident aircraft knew about the method of fog clearing and decided to implement the procedure with fatal results

[forget]

Thanks for clearing that up.

[Airways Ed]

As I just discovered this thread, a better late than never response...

In his book, Swissair im Kampf und Aufstieg, Robert Fretz, a captain and then vice-president operations, says that the fog dispersal procedure was developed by the sector chief pilot for Europe, Charles Ott, and the Caravelle technical chief pilot, Peter Baumann (p271).

That the heat from engine exhausts was able to disperse fog on the runway had already been discovered in DC-7 operations, and United Air Lines, among others, used this technique to improve visibility (p270). The procedure developed for Swissair’s Caravelles was used successfully in almost 50 cases between 1960 and 1962. What was proscribed was the continuous use of brakes while taxiing along the runway. The procedure was to stop two or three times on the way to the threshold (ie opposite to the take-off direction), run the engines up to 7,500rpm for 15 seconds, then taxi for another 1,500ft, repeat the run-up, then possibly repeat it again. Each time a tunnel about 1,500 to 2,500ft long, 130ft wide, and 30m high (100ft) was created and these tunnels joined together to cover the runway length required.

On 04Sep63, it was not certain that the crew actually executed the fog dispersal procedure because apparently the airplane never stopped on the way to the threshold. The voice recordings show that the main purpose was to reconnoiter the visibility over the whole length of the runway (which the crew reported to be very patchy). The aircraft was guided by a follow-me car, but the crew did address the pilots of a CV-440 that was preparing for takeoff after them that the jet blast on taxiing down the runway had probably made a difference. They then reported turning around to return to the beginning of the runway and probably take off.

A reconstruction under the auspices of the Eidgenössische Materialprüfungsanstalt (EMPA, federal materials testing institution) showed that wheel temperatures never exceeded 40°C (118°F), but Air France and SAS had experienced tire blowouts because sometimes only one of the wheels on a bogie provided all the braking force and therefore overheated (p273). However, never had a wheel overheated to the point of the wheel rim disintegrating as was the case with HB-ICV. The crew, as well as the airline, was exonerated in the accident investigation.

[zlin77]

Tee Emm,is this gentleman W.B.?