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Old 26th Mar 2011, 09:04
  #662 (permalink)  
Tagron
 
Join Date: Feb 2008
Location: U.K.
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I had hoped that someone could provide SEN runway specific data for the A319, but no such luck it seems. Rather belatedly I have managed to access the A319 Airplane Characteristics document on the Airbus website. The A319 take off performance charts here are somewhat vague in that they refer only to “runway length” and there is an anomaly in that the ISA+15 figures appear less restrictive than the ISA figures. Have the charts been transposed ? Or do the figures refer to variants operating to different maximum thrust levels ? It is not clear.

However, even with these caveats there is useful guidance here. Enter a runway length of 1750m and pressure altitude of 1000ft (a very conservative figure for SEN in summer) and we find that:
At ISA the maximum take off weight, performance limited, is 69.5 tonnes.
At ISA+15 the maximum take off weight, performance limited, is 71.3 tonnes.
Both approximate and not forgetting the anomaly above.

Reduce the runway length to 1500m (as an arbitrary artificial means of allowing for factors that we cannot properly evaluate) and these figures become 66.8T and 68.6T. That is another very conservative assumption.

Now look at the maximum certificated take off weights. The EZY aircraft are mainly 64T,though I understand some are 68T. BA A319s operate to 68T. In other words the 64T aircraft will not be performance weight restricted at SEN, the 68T version may also be unrestricted. So payload/range considerations are a function of aircraft type variant, not the runway.

The second segment climb may or may not be more restrictive than the other parameters such as TODA or max certificated TOW. It can only be evaluated by running the data. The most limiting of the parameters can change with differing ambient conditions and different TOWs. The operators' "performance engineers" can have various ways of alleviating the effects if necessary, such as scheduling an emergency turn.

And if a company really has a policy of operating only from greater than 1800m TODA but it considers it commercially attractive to operate from the 1799m declared at SEN, then a pragmatic solution to the missing 1 metre should surely present itself, especially as the “real” TODA is well in excess of 1800m.

It seems to me entirely reasonable that EZY should have looked at SEN and considered their options. Whether they decide to go ahead will be I suspect a commercial decision based on macroeconomic factors especially the UK economy, and company specific issues, such as the desirability or otherwise of establishing a new south east UK operation.


I have no view on the outcome. It is however clear enough that the extended runway at SEN will support a good portfolio of European routes by medium size aircraft.





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