Originally Posted by
Alpine Flyer
Operations-wise it's a tough call to decide between high speed and bad glide ratio to restart the engines or best glide speed but no chance of restart. A little less tough, whether to try starting the APU to have more equipment and usually more flight controls working.
If all engines fail, I’d be really hesitant to trade altitude for a windmill relight. If they both failed, I’d think there could be a high probability of being unable to restart them (fuel starvation/contamination, damage due to ice/birds/whatever). You can always try to restart them when you’re below the appropriate ceiling but the altitude (air time) you just traded off it’s not coming back. Starting the APU is an immediate action. Ask Sully.