Hi all,
suppose we have a TAF3 forecast with validity 0900/0918 which forecasts very bad weather at the start of the forecast period, changing to very good weather at 0100 (FM 0100), and our ETA is 0050 Z.
So we're forecast to arrive into bad weather, which will be replaced by fine weather only 10 minutes afterwards, during the first 3 hours of the TAF3.
My interpretation of the rules is that:
- for our ETA of 0050Z, we require either an alternate, or 40 minutes holding.
- if instead our ETA is 0100Z (only 10 minutes later), we would not require an alternate, and would not require any holding fuel at all.
With ETA 0050Z we are inside a forecast period of bad weather, which surely triggers an OPR.
Then AIP ENR 1.1 para 10.7.2.3 states that, if weather is forecast to improve above the minima, then instead of an alternate, we can hold until the forecast time when weather improves, plus 30 minutes. That's 40 minutes.
With ETA 0100Z we are inside a forecast period of good weather, and since it is within the first 3 hours of the TAF3, there is no OPR for this arrival time. (ENR 1.1 para 10.7.2.9 says we do not have to apply buffers of 30 minutes described in paragraphs 10.7.2.7 and 10.7.2.9). There is no OPR, so there is no requirement for alternate or holding.
This seems perverse. The requirements for holding fuel change abruptly. Wouldn't it be more logical to allow the pilot arriving at 0050Z to hold for only 10 minutes, until the forecast time of change? But 10.7.2.8 does not apply to this situation. Am I misinterpreting the rules?
If the forecast was an ordinary TAF rather than a TAF3, then for ETA 0050Z we could hold for 40 minutes, and for ETA 0100Z we could hold for 30 minutes, and the requirements would not change abruptly over time.
Help!!