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Comment by icefo | Hacker News Reader

I wonder if it was a fuel issue. The "we lost two engines" near the destination airport makes me think of that.

Based on pictures circulating on Twitter, it looks like the plane's engines may have scraped on the runway (presumably in a landing attempt without landing gear down) before taking off again.

Very unlikely, if the landing gear has problems to the extent that you scrape the runway with the engines, then taking off is almost impossible and useless, you just stop to a halt. If your landing gear does not extend and lock properly, you abort the landing way before touching it.

A gear-up touch-and-go has been done before though:

https://en.wikipedia.org/wiki/Mal%C3%A9v_Flight_262

The engines were mounted above the wings on that airplane, so they wouldn't have scraped the ground during the touch-and-go.

khuey's interpretation was my assumption too having seen the Twitter pictures of the damaged nacelles, and lack of landing gear, during the first go-around. The RAT being deployed suggested to me some sort of hydraulics fault too; or maybe engines had failed at that point?

So, what would you say caused that damage?

https://mobile.twitter.com/PlaneSpottersPK/status/1263810587...

To further elaborate (since it's the first time I'd heard about this system), the RAT ('Ram air turbine') as used on the A320 is a mechanism for generating power for flight-critical systems during emergencies.

A good default stance to take in situations like this (especially so soon after a tragedy) is that the pilot and crew were likely fully capable and well-aware of what they were doing.

[1] - https://en.wikipedia.org/wiki/Ram_air_turbine

That depends on when the pilots became aware that the gear was not down. If thier first indication was touchdown, then ya, taking off again isn't going to happen. But remember that these aircraft don't always respond instantly. Perhaps the pilots were aware some time before touchdown. They could have touched down half way through an attempted an abort, only just grazing the ground.

You are completely right, based on the pictures I saw this is most probably what happened.

This assumes experienced pilots who were paying attention and following the checklist. If they weren't and forgot the gear on the first pass they might have panicked and tried a go-around.

The A320 has a very loud gear up alarm, and it is one of 3 that cannot be silenced or disabled by any means.

Initial speculation (because that's all anything will be for weeks at the very least) and comments from other A320 pilots indicate what likely happened is they were attempting an intentional gear up landing, were too fast and burned up too much runway, and attempting a go-ahead. Raising the nose can cause the rear to hit the ground if you're close enough, and this would explain the charring on the bottom of the engine nacelles.

I'm not an expert (y'know, like everyone in any given HN comments section), but surely there must be automated systems in place that warn the pilots if the landing gear is not deployed when within x meters of the ground?

Yes there will be an automated warning. On the airbus it calls out "retard" below 20 ft. Edit: This wrong, see reply below.

"Retard" is a normal callout during touchdown. The gear up warning is a separate "too low gear" callout from TCAS.

"Too low, gear" (and the other terrain alarms) are from GPWS, not TCAS.

Thanks.

The RAT was deployed too, so clearly they were having power issues. Just haven't seen if they had power plant problems before or after the engines appear to have scraped the ground.

Not much more than an armchair flight engineer here, but even if there's a hydraulic failure, does the A320 have a failsafe mode where the landing gear can be deployed via gravity?

Yes, you can use the alternate gear extension mechanism to manually unlock the wheel bay doors and rely on gravity to pull the gear down and lock it into place. This sometimes doesn't lock the nose wheel (you'd have to be nose down a lot for it to work) but that's usually okay.

There were also multiple landing attempts, which supports that theory as well.

The FlightRadar24 plot shows only one go-around attempt, with a climb to 2,000.

I agree there's no indication of more than one go-around in FlightRadar24's data [1].

But during takeoff, the data shows the flight jumping from 0 to 1000 ft in a single measurement, so it's probably not as robust and granular as we might hope.

[1] https://www.flightradar24.com/blog/pakistan-international-ai...

Yea, ADSB rarely shows up on airplanes below 1000ft. On many of my flying lessons the Flightaware flight path goes haywire because it doesn't always pick up pattern traffic.

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