EL AL is having a rough couple of weeks. Last week EL AL was in the news for their horrible handling of a flight that ended up diverting in order to observe Shabbat, and now they’re in the news because one of their 787s took off 80,000 pounds heavier than calculated.
This incident actually happened on a March 29 flight from Tel Aviv to Newark, operated by a 787. The reason it’s in the news now is because Israeli investigators have just completed their investigation of what happened.
During takeoff, the flight struggled to get airborne. The plane “rotated” right around its stall speed, and it took 13 seconds from the time the plane rotated until it reached an altitude of just 35 feet (that’s something that usually takes just a few seconds).
So, what was the cause of this incident? As it turns out, the pilots incorrectly programmed the onboard computer. Pilots will enter all the weights into their onboard computer (they know how much the plane weighs “dry,” they know how much fuel they have, they use average weights for passengers, etc.).
In this case, though, they entered a zero-fuel weight of 128 tons, rather than 168 tons, so they were off by 40 tons.
Based on all the data the pilots entered they were given their takeoff speed, which is why they decided to rotate at 154 knots, rather than the 175 knots that would have been required with the plane’s correct weight. This meant that the plane rotated more or less at its stall speed, and this also caused a tail-strike protection system to activate.
The pilots only realized their error when they passed through about 20,000 feet. That’s because the onboard computer recommended an altitude of 38,000 feet rather than the usual 34,000 feet. This is the point at which their instincts kicked in, as they realized there’s no way the plane could reach such a high altitude so early in the flight (this is why on a longhaul flight you’ll find that you gradually climb, because the plane’s optimum cruising altitude increases the more fuel you burn off).
The investigation concluded that:
- The pilots were rushed, since the inbound flight arrived late
- The 787 is still a new plane type for EL AL, so that may have contributed to this, as the pilots may not have had the same “instincts” they’d have if they had flown the plane for a long time
- The first officer didn’t correctly cross-check the data entered by the captain
- They were taking off in darkness, which makes it tougher to discern the plane’s weak takeoff performance
This is an interesting incident from EL AL. The airline is known for their excellent pilots, and of course it’s easy to sit here and say “how the heck didn’t they notice the 40 ton discrepancy?” But humans make mistakes, and it’s fortunate that this ended the way it did. Hopefully it doesn’t happen again.