Originally Posted by
admiral ackbar
Not excusing what they did but apparently those types of N1 values (under 90%) are not uncommon on cold winter days in Canada. Does not mitigate the fact that they should have slammed the throttles at some point but perhaps that is part of the reasons they missed it initially.
Not even uncommon, depending on weight, in Europe during the summer. Lowest N1 i had in a 737 was 75% for take off, and that was well within the limits with a huge stop margin. Yes, derate plus assumed temperature, a 4000m runway and a short sector in a 737-700 helped there, but if you fly different variants, it is pretty much impossible to do a rough number crosscheck as you can see wildly different performance figures depending on options during the performance calculation. Even the V1 for the same conditions can vary by over 30kts depending on improved climb speed schedule or not.