Making an online booking of a Finnair flight with BA Avios is problematic right now. See for a recent discussion

https://www.flyertalk.com/forum/brit...-erroring.html

Leaving that difficulty aside for the moment, I have a question. In a previous life, I planned a number of mileage-based RTWs on *A. I often found that the distance from A to B to C that was used by the ticketing airline was different, sometimes significantly so, from the data available to me on, for example, the Great Circle Mapper. Now I am looking at making an Avios booking on AY from HEL to LHR. Does anyone know for a fact where that route falls, according to the award chart -- is it zone 2 or zone 3? Zone 2 goes up to 1150 miles. Zone 3 begins at 1151 miles. According to the GCM, HEL-LHR is ... 1151. But I wonder what the official BA opinion is?

(And for those who would say 'Why don't you just ring them up and ask?!?', the answer is that I refuse to submit to the whole security catechism rigmarole -- making a 30-second call into five minutes -- for such a simple, innocuous, impersonal question.)

TIA.