NavList:

Suppose Coutinho was a righty, and needed his right hand to fly the plane.

The Fairy IIID floatplane was a two seater.  Coutinho Rear Admiral Couthino was the Navigator and occasional Co-Pilot.  The Pilot was Commander Cabral.  Unfortunately, Cabral went missing in 1924, so didn’t live to enjoy quite the same fame outside Portugal which Coutinho received.  However, the aircraft would have been noisy, so it would have been easier for Coutinho to write down his own altitudes for which he might have preferred to use his right hand whilst still holding the sextant in his left.  Incidentally, I read somewhere that in fact they had a good natural horizon on the run in to St Paul’s Rocks, so didn’t need to use the AH on that occasion. DaveP