Delayed flights analysis
In the review by OFEV of the various documents concerning the CRINEN
decision of
The first method of investigation used was to look at all late night
movements in the summer period of 2009. This excluded the very disturbed
periods in winter, in which disruptions due to bad weather can affect movements
all over
The next step was to use GAME to retrieve, and put into two spreadsheets
(one for EasyJet
After the sorting, there were a few very late arrivals (ones for which
the scheduled arrival was a long time prior to 21h00), plus also a few for
which the scheduled arrival time was either unknown or doubtful (arrivals not
at all grouped around the arrival time as appearing in the official timetable
for Summer 2009. These were excluded from further study
The next step was to group the arrivals into the different weeks of the
year and look at the delay (negative for flights landing before their scheduled
time) in intervals of 5 minutes. These values were then used to make a
histogram plot of the percentage of landings within the different 5 minute
delay intervals, averaged out over the whole Summer.They
were also used as data for scatter plots of delay against week in the Summer
(weeks 14 to 43) for different days of the week or groupings thereof.
The histogram plots showed the expected asymmetric (skewed) distribution,
with a tail extending up to as much as two hours. In this respect, it is clear
that there might have been an even longer tail if some flights had not been
cancelled because they were refused permission to land after 0030. What was
quite surprising (and encouraging) was that the polynomial fits to these plots
showed that flights of easyJet UK had virtually the same good record of
punctuality as those of the classical airlines (though they would still have to
return to the UK), with both a median and an average near to zero. However, the
polynomial fit to delays of easyJet
The polynomial fits to the scatter plots for the different days might sometimes
have some errors if schedules had changed during the Summer,
but in general confirmed the relative lack of punctuality of easyJet
To try to gain a better understanding of what might be happening, a
detailed investigation was then done on five flights which regularly arrived
late in the evening. These were EZS1450, from
EZS1450, from
EZS1458, from
EZS8478, from London Gatwick, scheduled for 22h45 every night, has an
overall delay slightly less than the other two EZS flights, but again clearly
shows that the delay in the middle of summer can be about 20 minutes worse than
spring and autumn. It does not appear to have taken place on three nights.
LX2818, from
TP942, from
Although some investigations were made for several other easyJet
Switzerland flights which appeared to
have a rather poor punctuality record, it became rapidly evident that no one
flight was enormously worse than any other flight (though some seemed more
likely to be cancelled, or diverted, than others). This is attributed in part
to the fact that the 8 identical A319 aircraft can be, and often are,
rescheduled to try to avoid having any flights cancelled because they cannot
return before 0030. In some sense, easyJet can sometimes influence which flight
will be particularly late back by their apportioning of available aircraft to
required final rotations. However, this influence is more limited for longer
distance flights.
Thus, instead of looking at more late flights, it was decided to look at
a particular time period in order to see what flights (of all airlines) landed
or took off very late, or did not happen at all, and what were any particular
problems on the days concerned. An examination of the movements of the aircraft
involved, and even of other aircraft of the same airline, on the day in
question, perhaps also the previous day, may then provide a provisional
explanation. Of course, only the
The most obvious month to choose was March 2010, which has been stated
to be normally the busiest month of the year. For this month it is then easy to
use GAME to extract a list of all takeoffs after 23h30 and all landings after
24h00. These aircraft movements are generally at least an hour behind their
schedule (if this schedule is known). The two lists are attached to this
document.
The first action was to check whether there were any regular flights
which, whilst scheduled, did not appear to have taken place. This was the case
for the flight BA738, from London Heath Row, on 20, 21, 22, 27, 28 and 29
March, due to industrial action by BA personnel
Landings after
There were 10 landings between 00h00 and 00h30, of which 5 were of
easyJet
ARAG has no idea why this last flight from
ARAG has no idea why this last flight from
On the morning of 7 March, only 7 of the 9 required aircraft were
available (HB-JZM stayed in
One can therefore suppose that two easyJet aircraft had some technical
problems
ARAG has no idea why this last flight from
ARAG knows of no particular reason for this very late arrival. Perhaps
it was related to the industrial action by cabin crews of the airline.
Although 10 aircraft of easyJet
The accumulated deficit was spread over the incoming flights of the last
9 rotations: all were late or very late, with this flight back from
It is not known to ARAG why the two aircraft were not used until late in
the day.
This was the first day of the 2010 summer schedules, also a short night
(the night that the clocks went forward. It was clearly a difficult day for
easyJet
One basic reason seems to be that the aircraft HB-JZQ made only two
rotations (to
In addition to the above, the aircraft HB-JZH left rather late for the
final Gatwick rotation, but did not return from there until the following day
(at 09h27 as a ferry flight), and the aircraft HB-JZQ only operated the
following day from about
One can suppose that perhaps the aircraft HB-JZQ had some kind of
problem.
ARAG has no information why this aircraft came in so late. It is
interesting, however, that the operator of the aircraft concerned has announced
on its web site that Michael Schumacher will be using its services in 2010.
Takeoffs after
23h30 in March 2010
There were 10 takeoffs after 23h30 in March 2010, of which exactly half
(5) were of regular scheduled airlines operating from
Of these last four, one in particular is rather disturbing, being a Gulfstream III, which is believed to classified
as noise class II, took off at 23h48 on 27 March. A request to the aircraft
owner for any explanation has not been answered.
These takeoffs will be discussed in chronological order. Note, however,
that if the time is after
On this day, for some reason the aircraft HB-JZI did not operate. It
appears that the first morning flight to London Gatwick was cancelled, whilst
the return was operated by the UK aircraft G-EZBK, which was then used for
three Geneva rotations, ending with a the final Gatwick rotation, arriving back
at 23h13. The aircraft then went back to Gatwick as a ferry flight.
It would perhaps have been preferable if this ferry flight could have
been done next morning!
On the 6 March one aircraft (HB-JZK) came back very late in the
afternoon after only one rotation (to Marrakech). Another one (HB-JZM) also
came back very late in the afternoon after just a second rotation. This clearly
left a shortage of aircraft for that evening. Although two Gatwick services
were handled by UK-based aircraft, it seems that the final Nice
service was cancelled and the aircraft which went late to
The use of the UK-based aircraft involved also a reversal of the final
Gatwick service, with the result that the final flight to Gatwick (a UK-based
aircraft returning to
The aircraft (G-MIDY), based in London, made three rotations of
London-Geneva-London and progressively fell behind schedule (in particular the
first stop in Geneva, when it took 2 hours to turn around, instead of the usual
one hour). There may have also been delays in
A Geneva-based aircraft of Swiss, also doing 3 rotations to London
(LHR), lost an hour during the day.
As already explained in the explanation of late landings on 7 March,
some apparent
unavailability of easyJet
It would have been better if easyJet
No information available. The aircraft may have been a charter
operation: it typically seats less than 20 passengers. The company has not
responded to a written query for information.
The company has responded to a written query for information, stating
that the client needed to arrive in the
The incoming EZY8559, scheduled to arrive at 20h55, only landed at
23h11. ARAG cannot know the reason for this.
ARAG has no information on this. Since the aircraft was a Boeing 737, it
was very probably a charter flight.
ARAG has no information on this. A written request to the owners for
further information has not been answered.
The aircraft concerned appears to be a Gulfstream
G-1159A, built in 1981. ARAG understands that this aircraft is in noise class
II. It is surprising, and regrettable, that such a noisy aircraft can depart so
late.
ARAG has no information why this Falcon 2000 left so late.
Conclusions
All of the graphs tend to suggest that punctuality is less good in the
middle of Summer than in the Spring and Autumn, and
that weekends tend to be worse than weekdays. This is particularly noticeable
for returns of easyJet aircraft, suggesting that the holiday destinations which
they serve may be under pressure in the middle of Summer.
The examination of the late flights in March 2009 shows two disturbing
patterns: the problems which easyJet may face when their complete fleet of 9
Geneva-based aircraft are not always in use and the relatively large number of
late departures which are unscheduled and operated by small business jets.