EFB OPT
The potential for error with the OPT is substantial. A latent risk factor within a defined process is difficult to detect. SOPs may provide for the flight crew independently working all of the calculations out, but operational expediency tends to result in short circuiting of such protocols. A takeoff chart gives some level of awareness of the overall situation, but it still is open to errors, in fact, more error opportunities exist.
The good news is that indeed two engine aircraft tend to perform well, on two engines, but 8500' at heavy weight is a tough deal for a 773ER, at sea level at warm temperatures. If the engines work, you are doing OK, the same error on a B747 A380 would be catastrophic, AEO liftoff is not much earlier than OEI case, and so normally happens well beyond mid field and towards the DER.
Part 25.113(a)(2) requires a 115% margin for distance to attain 35' for the TODA. So for say a 12,500' runway+clearway, the 35' point is at 1630' before the end of TODA. For a large aircraft, the aircraft is also assumed to be at V2 plus a maximum margin, but more importantly a minimum margin of V2 (25.111(c)(2)) ... which is going to be around 90m/sec ~ 300FPS. That means about 5.3 seconds after getting to 35' you should be passing the end of the clearway. On all engines, the 4 engine aircraft, and 2 engine aircraft as well have climb rates of around 2000FPM or greater, (minimum 2nd segment gradients apply for OEI, 25.121(b)(1)... all is better...), which gives about... 210' above the departure end of the TODA (35'+175'). In the real world, the speed is allowed and does rise above V2, and the outcome is that there is an initial reduction in the climb gradient until establishing a constant target speed, but the rate of climb once established is higher than V2's rate of climb. Overall, the crossing altitude is slightly lower, around 180'... So... when you look out the window and see the neat takeoffs that just get over the fence, know that if the aircraft had done a reject, that probably would end badly, and if the aircraft isnt getting to the types of heights that the all engine case shows, (and which are noted as information in every Boeing FCTM) then you do well not to have an engine failure. If you want to take the analysis a step further, the FCTM also indicates the time to achieve liftoff after commencing rotation, and that gives you a simple spot on the runway where the rotation should occur. The same manual, the FCTM also gives pretty simple analysis of the visual cutoff from the cockpit, and that gives a simple indication as to what should and what should not be observable in front of the aircraft as you reach Vr. As an example, for a B744, that is around 3800' from the end of the TODA if you are on a limiting 12,500' runway, with maximum clearway. Rotate gets to be done around 2 seconds before you lose sight of the first of the TDZ markings for the opposite end of the runway. For the B777, and other twins, you get much more runway in front at that time... should not be exciting at all on all engines, just gets more interesting with the failure case.
Bottom line is that awareness of the performance of the aircraft is worth the effort, even if you don't get comfort from the outcome. Lets see... B773ER, 6700nm GC route right hand down... making money... TOW will be over 725,000lbs, and need over 9200 ft of runway, (still air, 300 pax, 12T cgo... ). still air, 490K ZFW would need 10,500' ISA +15 SL, 0WC, packs off... Stated as a ZFW limit, the T1 taxiway would need a 440K ZFW in still air, and that would increase by around 15K per hour of flight time reduction from still air.... i.e., +390 lbs per knot of TWC overall on the flight plan... None of these
calculations are hard, and they can be done by the system easily, and provide the flight crew a choice of acceptable options which they confirm with the OPT.
Final point, this latest event is more or less a rerun of an event that I personally experienced from the cabin of a B777 once while dead heading. Being aware that the runway being used is too short is pretty unpleasant to experience. luckily on the day, the workers on the runway ducked. Crew even took a derate... The company involved eventually examined the issue, and held the pilots accountable, for known deficiencies in the processes and practices of the system; hardly a global solution and barely surprising management behaviour for a pathological flight operations department.
Short runways and big airplanes on long flights don't mix, and if the computer says they do, then checking the assumptions is probably what your family and customers may appreciate. Big picture prior to walking to the jet is worth the effort, there is a relatively simple correlation between weights and runways that can be considered before leaving the hotel or the despatch office...
The crew of this flight should not be beaten up by the management for a latent error, however, the flight crew are the guys and girls at the pointy end of the spear, and they have a vested interest in keeping the blue side up, they are the first to the scene of the accident. Punitive response by management would be adverse to flight safety, but is pretty much a standard industry response; shooting the messenger is untidy and hardly improves outcome reliability.
Will QR and the QCAA improve operational flight safety? Always interesting to see.