Re: In the air?

Date:         28 Mar 98 14:21:45 
From:         Andrew Cruickshank <>
Organization: OpenKast Limited
References:   1 2 3
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Karl Swartz wrote:
> >Some airlines like BA get in the range of 15 to 17 hours/day
> >of flight averaged over the lifetime of their 747-400s. This would
> >imply that two thirds of their 747-400s are in the air at any one time.
> If true, that's pretty impressive, but most of those planes are too new
> to have seen their first D check, which will put them on the ground for
> a big chunk of time.

The figure may also be better for some of the earlier aircraft if they
were used on specific optimal routes. One thing I have noticed is that
BA do seem to turn their aircraft around quite quickly at the endpoint
of the route compared with some other airlines. This may be clever
scheduling (and slot acquisition/management) as well as more efficient

> I happen to have the NTSB report for UA 811 at hand.  That's the United
> 747-122 which blew a cargo door about an hour out of HNL on February 24,
> 1989.  The aircraft was delivered on November 3, 1970, 6988 days or
> approximately 160,512 hours before the accident.  At the time of the
> accident, the aircraft had 58,815 total flight hours (and 15,028 cycles).
> That gives an average daily utilization of 8.8 hours over 18+ years.

I spotted an ad from Air India in Flight back in January selling four
747-200s. They only gave a year of manufacture (which I have subtracted
from 1998 - therefore assuming a whole year of operation during the
manufacturing year - but this only gives an error of around 5% anyway
on the youngest aircraft).

        Age        Cycles       Hours      hrs/day      hrs/cycle
        27         22585        75019        7.6          3.3
        26         22093        73595        7.7          3.3
        23         17779        62913        7.5          3.5
        19         14493        51829        7.5          3.6

The low hrs/cycle is probably due to routings through say Paris CDG
to LHR from Delhi where there is a reasonably long segment followed
by a short hop.