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Again, at the beginning of the 90’s, when the fuel prices increased prior to the Gulf war,
certain IATA members expressed a wish for the freezing point of JET A1 (-47°C
maximum) to be relaxed to the JET A level (-40°C maximum), hoping that this would
make more kerosene available from crude oil and cause the fuel price to fall.
According to fuel suppliers, such a relaxation could potentially increase jet fuel production
by about 8%. Nevertheless, they all agree that, for various reasons, this is a theoretical
figure that cannot be guaranteed and that would not necessarily make jet fuel cheaper.
Consequently, a change in freezing point should be based on technical requirements and
not solely economic factors.
As a result, IATA member airlines were asked to monitor in-flight fuel temperatures during
long flights.
The result of this survey led, in 1992, to a general consensus that a change in the fuel
freezing point specification from -47°C to -40°C is not acceptable due to flight safety and
economic operation aspects which would be adversely affected by such a change.
D4.2 Fuel temperature encountered in flight
This survey highlighted that many international routes could not be flown using JET A without running into problems.
Figure D4
shows the result of a survey performed in wintertime by an A310 operator on Trans-Siberian routes, which covers one of the most severe low temperature sectors.
These graphs prove that JET A (having a freezing point of -40°C) is inadequate on such routes.
132
SVO - NRT (FL 332 / 364 - 14 flights)
NRT- SVO (FL 314 / 348 / 381 - 13 flights)
Figure D4 - A310 fuel tank survey - December 91 - February 92
crew received the Low Temp Advisory (LO) requesting to transfer outer tank fuel if JET A is used.
Figure D5
D5 ACTUAL FUEL FREEZING POINT
Being aware of the exact value of the fuel freezing point may bring some benefit when establishing a flight plan or when the crew has to decide whether or not flight conditions have to be altered according to the actual fuel temperature.
D5.1 Fuel freezing point value
As previously mentioned, when known, use of the actual fuel freezing point of the fuel being used may be considered instead of the maximum value authorized by the fuel specification. This may of great benefit because suppliers generally produce a fuel with a significantly lower freezing point than that required by the specification.
For example, a survey on JET A fuels made from 1990 up to 1992, showed that the average fuel freezing point of JET A was -44.5°C (for -40°C maximum allowed) with minimum values lower than - 60°C. A similar survey conducted by .Phase Technology. (a Canadian company involved in research in cold temperature behavior of petroleum products) between July and September 1998 on JET A fuels in six US majors airports showed the following results (all temperatures in °C):
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