The Prestwick Air Disaster

[Coast]

Prestwick airport's exceptionally good weather record is the reason that KLM New York flight from Amsterdam (aircraft registration PH-TEN) is stopping over, tonight, in 1948. Sandwiched between two seaside resorts on the Ayrshire coast, Prestwick's almost guaranteed fog-free status is why it is the only Scottish airport granted a prestigious transatlantic link in these earliest days of civil aviation.

Tonight's incoming Lockheed Constellation, Nijmegen, (the first pressurised civilian airliner, which brings flying to the masses) is captained by K.D Parmentier, KLM's chief pilot - widely regarded as one of the great flyer's of the era. For once however, Prestwick's celebrated micro climate is not so ideal. The weather has steadily deteriorated all evening and as the KLM flight approaches, the airport is under drizzle, the cloud base almost solid at 600 feet 200 metres).

Parmentier unfortunately doesn't know this - a delayed take off from Amsterdam means he misses the radio message - or he would certainly have diverted to Shannon in Ireland. Nor does he receive Prestwick's Morse weather warning on approach, because he has now switched to voice contact. Descending to land, with the main runway lights visible, Parmentier is, in any case more concerned with cross-wind than visibility. He negotiates with air traffic control to use an alternative runway, one that KLM guidelines - drawn by Parmentier himself - expressly forbid using in low cloud. Parmentier of course in the dark, believes there is no low cloud

The errors now come thick and fast. Over-flying the original runway, Parmentier climbs ready for his new approach and enters cloud Assuming it's just an isolated patch, and expecting to see the runway any moment, he takes none of the the usual cloud-flying precautions. As he heads blind, for higher ground, the lowered landing gear of the Constellation strikes the main phase conductor of the, 132,000-volt cables of the Scottish National Grid. Parmentier radios: 'I have hit something, going on fire, attempting m climb.' It's his last message The aircraft crashes and explodes. All thirty four passengers and crew are killed. Parmentier is found, still trapped in his seat many yards from the aircraft.

The fight is (excluding Lockerbie in December 1988) Scotland's worst air disaster.

Taken from the book 'The wrong kind of snow' Woodward and Penn

The subsequent court of enquiry blamed several factors for the crash:

The failure of the ground authorities to inform the Nijmegen of the deterioration in the weather.

The failure of the crew to time their flight downwind of the runway.

The errors in the official KLM approach chart the crew had relied on. It emerged these charts had been copied from war-era United States Air Force charts, which upon subsequent examination were also found to be faulty. The court of enquiry was astonished to find that KLM had relied on maps from a foreign authority when detailed and correct maps were available from the Ordnance Survey.

The following probable cause was determined:

1. That when the pilot started his landing manoeuvre for runway 26 of Prestwick Airport the weather conditions were already below the limits for this manoeuvre but that from the weather forecasts received this could not be known to him and that this could not be personally judged at the time.

2. That, although the landing on runway 26 under the weather conditions, as far as these were known to the pilot, required the greatest caution, the pilot could not be blamed for having commenced that landing procedure.

3. That flying too long on the downwind-leg of runway 26 caused the accident.

That, if no unknown circumstances contributed to the extension of the flight on the downwind-leg of runway 26, the extension was due to the delayed action of the pilot after he lost visual approach.

4. That it was not impossible that a stronger wind that the pilot accounted for contributed to the extension of the flight on the downwind-leg of runway 26.

5. That the possibility of other circumstances as mentioned under 4 could not be ruled out, but that no data was available which could give cause for the supposition that they contributed to the extension of the flight at a low altitude on the downwind-leg of runway 26.

en.wikipedia.org/wiki/

Take-off from Schiphol was planned at 20:00 on 20 October 1948 for a flight to New York via Prestwick, with as alternative Shannon, Ireland. The Constellation PH-TEN Nijmegen, with thirty passengers aboard, carried enough fuel to return to Amsterdam after such a diversion. Weather for Prestwick was bad, but improving, according to the forecast; in actual fact, conditions were deteriorating. Take-off was delayed to 21:10 while additional cargo was loaded for Iceland, with an extra stop planned. Because of this delay, the wireless operator missed (by five minutes) a Prestwick radio message advising of rain and a 600 feet cloud base.

Under these conditions, in combination with a 20 knot cross-wind on the main runway, KLM-pilots were forbidden to land at Prestwick, instructions drafted by chief pilot Parmentier himself. There were more dangers at Prestwick: Inland of the runway the ground sloped upwards to a height of over 400 feet five miles to the east. Three miles to the north-east the tops of the wireless masts reached almost 600 feet. Three miles inland a high-tension line ran north to south at 450 feet. Parmentier knew Prestwick quite well and himself had written all these hazards up in the KLM route manual.

The routine weather reports, not forecasts, picked up during the flight gave a cloud cover of 700 feet. When Parmentier contacted Prestwick Approach Control by voice radio shortly before 23:00, he still did not know about the forecast drizzle and low cloud base. He also was not aware that the cross wind on the main runway had dropped from 20 to 14 knots, which made it within limits to use without having to land on the shorter Runway 26. Nor was he told that two large SAS airliners had turned back to Copenhagen instead of attempting to land at Prestwick.

www.cyberbore.com

The court of enquiry concluded that "a pyramid of circumstances" had produced the tragedy.

"First there was the complete absence, in the radio messages and conversations between aircraft and airport, of any reference to a deterioration in the weather. Second was the failure of the crew to employ a timing procedure when flying downwind of the south-west runway—Runway 26. Third was the false and misleading character of the chart in use. It transpired that these charts had been copied from American Air Force maps, which must also have been faulty. The court expressed astonishment that such maps should be based on a foreign authority when detailed and accurate Ordnance Survey maps were available."

[johnholmes]

very interesting reading that account-I had always understood that they blamed the Met observer so I'll go and scout round to see if I can get anything about that. Certainly the observer concerned was judged not to have done what he should have by Met and it led to a range of new regulations for weather observers at airports?

[Ross B]

Very interesting read of a local event. Cheers for posting that as i don't think I have heard of it before!

[johnholmes]

I cannot find the actual official board of inquiry report, the AIIB has no link to anything that long ago.

[Coast]

I don't think the AAIB records go back that far online John. You can probably order one through the British Library (as I did for the EI-BGL crash in Eastbourne). More pictures and some more information, if your Dutch is good try here: www.hdekker.info!

In summary, the Official Enquiry brought to light the fact that Captain Parmentier had not been briefed adequately or accurately on current weather conditions by Approach Control at Prestwick. The pilot was under the impression that cloud cover for approach to runway 26 was above the minimum safe altitude for final approach and landing (700ft / 213m). In fact, on that night, the cloud ceiling descended to about 300ft / 91.4m—a completely unsafe level for a night approach and landing on runway 26.

www.aircrashsites-scotland.co.uk

[johnholmes]

I don't think the AAIB records go back that far online John. You can probably order one through the British Library (as I did for the EI-BGL crash in Eastbourne). More pictures and some more information, if your Dutch is good try here: www.hdekker.info!

ta , I might try that