I am not sure that waiting to check your other tank until a "safe altitude"
is the best procedure either--if it is blocked for some reason, I would
rather have known about it before takeoff.

My procedure is to always start the engine on the left tank. Once the engine
is smoothly running, I switch tanks to the right before taxi to the run-up
area. That way there is plenty of time before takeoff to ensure that the
right tank is also feeding well. I would agree that just prior to the
takeoff roll is NOT the time to make and initial tank switch.

Doug Johnson

"Another potential common problem may be a defect in the procedures. I have seen pilots select the fuel tank in the before take-off checklist. That is a dangerous practice. Any fuel contamination or improperly selected valve may manifest itself late in the takeoff roll or shortly after takeoff. The before takeoff checklist should only be VERIFYING that the correct tank is selected. If changing the tanks is required, taxing back and doing another run-up may be in order.

My personal procedure is to select the tank before engine start and then not change it till I am at a safe altitude. This means the takeoff happens on the same tank that was used for taxi and run-up. Hopefully any problems like fuel contamination will become obvious long before the start of the takeoff roll.

Regards,

Hamid"