For the cabin crew it is part taxed and part tax free - I would expect the pilots to be the same.
On the pay slips it shows as two seperate entries - example shown below:
Sector Pay NTaxable (Then non-taxed amount)
Sector Pay 1 P&T (Then taxed and pensionable amount)
The tax free portion is greater than the taxed portion (certainly is for cabin crew anyway
).