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Aviation History
1961
1961 - 1853.PDF
FLIGHT, 21 December 1961 967 A large number of light aircraft are being imported into the UK by air these days, mostly by BOAC and PanAm DC-7Fs and Seaboard Super Constellations. Vigors Aviation have been a large user of these services; all their Piper Colts have been air-freighted so far, and now the new Piper Cherokees, one of which is shown here outside the BOAC freight shed at London Airport North in its 1962 colour scheme 2,000,000 JET HOURS IN Flight for February 10, 1961, we published an article entitled"Now a Million Jet Hours," in which a method of assessingaircraft accident rates was suggested, based on total losses per 100,000 flying hours. It was shown that, on this basis, jet air-liners were destroyed during their first million hours at roughly twice the rate at which propeller-driven airliners were being des-troyed. The prediction was made that "the two million jet-hour mark may well be reached before the end of 1961, possibly two orthree months before the end." During the last few days of October, just over three years sincethe Comet 4 and Boeing 707 were first put into service, total jet airliner flight time on all types passed the two million hours mark.How has the second million turned out from an accident point of view, and how does the overall jet record now compare with thepropeller driven types? It will be recalled that, during the first million hours, nine jetswere totally destroyed. Five of these losses occurred on training flights, and, because of this, it was suggested that the record mightreasonably be expected to improve. There has in fact been a slight overall improvement, using the total loss rate as a measure, althoughin some respects the position could be said to have deteriorated. The number of total losses during training fell to zero in the secondmillion. (The Lufthansa 720B training accident, though shown in the table, occurred after the 2,000,000hr mark.) However, onpassenger services, seven aircraft were totally destroyed, compared with four in the first million. Losses thus fell from nine to seven. By mid-December, jet flight time stood at approximately 2.25million hours, and aircraft destroyed totalled 18. So, on average, there has been a total loss every 125,000 hours. As was mentionedin the previous article, a comparable figure for medium/long haul piston-engined transports, for the three-year period 1956-58, wasone total loss per 300,000 hours. A comparable figure for all types of non-jet airliners was one total loss every 200,000 flying hours. A study has since been made of the lOyr accident record ofDC-6/7 and Super Constellations—which, by and large, the jets have replaced—and the total loss rate was again found to beapproximately one in 300,000 flying hours. This shows that the three-year period 1956-58, used previously as a basis of comparison,was not by chance an above-average period, and it suggests that this is the sort of rate which could fairly be regarded as a target forthe jets. In this light the jet record to date of one total loss per 130,000 hours cannot yet be regarded as satisfactory. But it mightbe argued that it is hardly fair to include the first year or two of jet operations in a current analysis, as a settling-in-period is onlyto be expected. In that case, |let us consider the last 12 months of operations (mid-December 1960 mid-November 1961). In thisperiod 1.4 million jet hours were flown, and 11 aircraft were des- troyed, making the total loss rate one per 127,000 hours, which isnot substantially different from the average based on total jet flight time since operations began. Turning now to fatal accidents, hi the first million hours therewere four accidents in which a total of 114 passengers were killed. However, only two of these accidents involved large loss of life,whilst in the other two only one passenger was killed in each case. In the second million hours there were also four fatal passengeraccidents, but each accident unfortunately involved large loss of life, and 199 passengers were killed—nearly double that in thefirst million. Since the two million hours mark was passed, there has been a further fatal passenger accident, bringing the totalnumber of fatal accidents to date to nine. This give a fatal accident rate of 0.41 per 100,000 hours. ICAO figures show that during the five-year period 1956-60,the world-wide accident rate for scheduled services for all types of aircraft (including the jets from October 1958 onwards) varied frombetween 0.34 and 0.36 with the exception of 1959 when the figure was 0.29. Measured in this way, then, the jet fatality record sofar is roughly 20 per cent worse than average. But this does not necessarily indicate that it is less safe to travel by jet. Safetycan be expressed hi a variety of ways, and as was mentioned in the previous article, each method has its own advantages and dis-advantages. For instance, preliminary ICAO figures for 1960 show that the jets had 1.01 accidents per 100 million miles flown, whilethe comparable figures for turbo-props and piston-engined aircraft were 1.78 and 1.79. It is probable also that because of the higherproductivity of the jets, the fatality rate per 100 million passenger miles is as good as that for propeller-driven aircraft. It is likely that by the end of 1962 total jet flight time will havereached four million hours. Although this will be almost double the present jet total, jet flight time during 1962 is still unlikely to TABLE I: JET FLYINC HOURS (Revenue and Non-revenue) Estimated as at mid-December, 1961 Boeing 707 DC-8 Comet 4 Caravelle Convair 880 1,100,000 570,000 260,000 240,000 85,000 2,255,000 TABLE 2: JET AIRLINER TOTAL LOSSES Date 15. 8.59 27. 8.59 19.10.59 19. 1.60 20. 2.60 23. 5.60 16.12.60 19. 1.61 28. 1.61 Operator and Aircraft Location Circumstances American Airlines Boeing 707 Aerolineas Argen- ' tinas ! Comet 4 I Braniff/Boeing ! Boeing 707 SAS Caravelle Aerolineas Argentinas Comet 4 Delta Air Lines Convair 880 United Air Lines DC-8 Aeronaves de I Mexico I DC-8 I American Airlines Boeing 707 Grumman Field, Long Island Nr Asuncion, Paraguay Nr Everett, Washington Nr Ankara, Turkey Ezeiza, B.A. Atlanta New York Idlewild, New York Crashed on approach ! during training flight 1 Crashed several miles short of runway on : approach Three engines torn off while on training and acceptance flight Struck hill on schedul- ed passenger service Crashed on landing while on training exercise Crashed on take-off on training flight Mid-air collision Take-off accident Off Long Island! Crashed during train- I ing flight Fatal i- t *rw 5 1 4 7 4 7 4 6 es Pas. — 1 — 35 76 — 1.000,000 hr 15. 2.61 24. 4.61 30. 5.61 11. 7.61 27. 7.61 12. 9.61 28. 9.61 Sabena Boeing 707 Japan Air Lines DC-8 KLM-VIASA DC-8 United Air Lines DC-8 Air France Boeing 707 Air France Caravelle Varig Caravelle Brussels Tokyo Nr Lisbon Denver Hamburg Rabat Brasilia Crashed near airfield after series of un- usual manoeuvres Over-ran runway on landing. Construc- tive total loss Crashed into sea Landing Swung on take-oft and collided with building Crashed near airfield when preparing to land Crashed on landing and caught fire II 14 — 6 — 61 48 16 72 — 2,000,000 hr 23.11.61 4.12.61 Aerolineas Argentinas Comet 4 Lufthansa Boeing 720B Campinas Airport W. Germany Crashed immediately after take-off Nr Ebershein, Crashed on training flight 12 40 Totals | 84 | 349 amount to more than 20 per cent of the flying time amassed on theworld's scheduled services during the year. Looked at in this light, total jet operating experience is stillrelatively small, and it must be hoped that, as experience grows, the jets will settle down to an accident record at least approachingthat of the aircraft they have replaced, and that ultimately they wiS improve upon their predecessors. ALAN E. SMITH
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