[Hogmann]

Originally Posted by Roosta ↗

What's your rating

I could make up any sort of answer here if I wanted to be a blow hard on the internet like you. But I'll give you an honest answer and if you think this isn't qualified enough then you don't know what you're talking about.

FAA Commercial ASEL AMEL ASES CFI CFI-I.
I have over 3,000 hours and more than 2,000 hours in turbine aircraft more than 2,000 hours as pilot and command I flew over 500 hours in the last year and am an instructor pilot at a part 135 operation where I provide instruction to new hires and Captain upgrades in both the aircraft and a Level D simulator.

Your turn.

[Hogmann]

Originally Posted by Roosta ↗

I would say that he popped the brakes in the wet conditions...

Since you've decided to take the approach of berating other's comments, let's just dive into this ridiculous comment a little more.
The runway conditions absolutely were wet. if you brake too hard in wet conditions you hydroplane (skidding) and the brakes lock at which point they're not doing any more work, the wheel is just stopped. as far as the braking system is concerned it's the exact same thing as if you stood on the brakes hard while parked. I challenge you to go out in your car or aircraft or any other piece of equipment and stand on the brakes as hard as you possibly can and get them to "pop." It just won't happen. Now maybe the brake pedal will slowly sink to the floor which is indicative of a defective brake system. In fact this is exactly what mechanics do when they assess the conditions of your brakes. what a coincidence. Now the cj1 does have an anti-skid feature which helps prevent wheel locking and hydroplaning. It is possible that there was an issue with that system. But I'm not aware of any widespread issue with the CJ 1s anti-skid system.

Since you seemed to miss it the first few times I said it the reason this accident happened is 600M just isn't enough runway not even in dry conditions. Now maybe this pilot hot dogs it and sets it down early before the threshold and has done this before on a dry day but that's not the case here. Also look at the sky conditions, that's an IFR day with ceilings less than a thousand feet there are no instrument approaches at this airport either. So the primary cause of this accident is the pilots attempt to land on a Runway that was too short. Probably scud running to stay out of the clouds making a short and tight approach resulted in coming in way too fast. Which only exacerbated the fact that the runway wasn't long enough . Was there some problem or failure with the brake system that contributed to his overrun? Possibly but the brakes didn't "pop" nor was that the primary cause of this accident.

[akham]

Originally Posted by Hogmann ↗

Since you've decided to take the approach of berating other's comments, let's just dive into this ridiculous comment a little more.

I've added them to my ignore list because their mental health problems are just that, their problems, and I see no reason for me to bother with it.

[Mr.NoCredit]

Interesting thread. Learned quite a bit.

Thank you both, akham and Hogmann, for the fun time learning a little about aviation today.


An educational post!

[akham]

I have done some further research into this accident. While we don't know the full story at this stage, pending completion of the investigation, it is obvious that the landing distance available was a major, if not the primary, factor here.

There has been a lot of questionable information/comments published (both here and on the Internet generally) about this incident so I have gone and found the actual primary, authoritative, source of information in respect of the landing distance required for the Cessna Citation CJ1+ in various conditions.

That authoritative source is the "Citation CJ1+ Flight Planning Guide" published by Cessna themselves. A copy of it is attached to this post.

The most relevant part is page 20, which lists the landing distance required under the following conditions: flaps set correctly, dry runway, airport at sea level (the landing airport is at sea level).

The table lists landing distances in feet for various temperatures and aircraft weights. Temperature readings I can find for that area at the relevant time (e.g. see the METARs I posted above) say the temperature was 24 deg C. That is about the average for the area in January.

So let's work with temperature = 25 deg C (closest temp shown in the table).

We don't know what the aircraft weight was, other than it had (apparently) the maximum load of passengers. So we will consider a range of weights and therefore landing distances.

The range of landing distances are 2,240ft (7,500lb landing weight) to 2,660ft (9,900lb landing weight). Remember, these figures are for a dry runway, and we know for sure that the runway was not dry at the time (refer video of the incident).

Converting into metres - the landing distance required would be between 683m and 811m (dry runway).

BTW, these figures are for Part 91 operations (general aviation). For Part 135 (air carrier) operations the landing distance is much longer due to higher safety margins.

The official AIP (aeronautical information publication) for the airport, published by the Brazilian Government, is attached. It lists the runway length as 940m long and 30m wide.

If a pilot isn't paying attention and not considering the weather, they might conclude that they can land their CJ1+ at max weight (needing 811m) on runway 09 (940m long).

However, if you read further down the AIP to DECLARED DISTANCES you see that when landing on 09 the first 380m is closed for landing. If that is taken into account, the actual landing distance available (560m) is not enough, even if your aircraft is effectively empty at landing (requiring 683m).

Even worse, the runway is wet. The adjustment factors applied when the runway is damp or has pooled water can vary, but the information I found indicates that Cessna specify factors of 1.45 (wet runway) and 2.25 (standing water).

Therefore the required landing distance for the aircraft would be between 683 x 1.45 = 990m (empty, wet runway) and 811 x 2.25 = 1,824m (max weight, standing water).

This is why I think discussion about any other factors, if any exist, are pointless because on those numbers if you are landing your CJ1+ on a wet runway 09 you are fucked (technical term) no matter what else is going on.

BTW, the CJ1+ does not have thrust reversers but attenuators can be fitted as an option. Photos indicate they were not fitted to the accident aircraft.

[Hogmann]

akham great info!

[Hogmann]

Denys make some good observations here but I think he's reading the landing performance wrong. It seems like the shortest possible distance the plane could land in and this plane had five people in it so it's going to be a little heavier than what would be required to make minimum Landing distance

[akham]

Originally Posted by Hogmann ↗

Denys make some good observations here but I think he's reading the landing performance wrong.

For a start he is using landing performance data for an aircraft with attenuators, which the accident airplane did not have.

I agree that he appears to be referring to figures for min weight, which would not apply on this flight.

[Roosta]

Originally Posted by Hogmann ↗

Why are you such a blowhard? I stated in my first comment exactly what went wrong here the runway was not nearly long enough for that plane to land on. And get your facts straight, the runway was 900 M long but the LDA was 600. (That stand for Landing Distance Available for the non-pilots)
I asked a simple question because I've never heard the term popping the brakes. I appreciate your picture of a Skyhawk having maintenance done on its brakes but that's not applicable in this situation.

I've heard of popping tires, either from locking the tires and burning through the rubber or by generating so much heat during braking that the fuse plugs melt and deflate the tires to prevent them from exploding, but that happens long after the landing. It's also possible to generate so much heat that you boil the brake fluid which causes it to leak out, but that takes repeated overuse.

But a catastrophic failure of the brake mechanisms because of hard application isn't a thing. Not in airplanes and not in cars.
One of my hobbies is performance track driving and I've used my brakes to the complete limit multiple times in my cars never once have I had the brakes "pop".

I have overheated brake fluid brake discs and pads and experienced break fade but never brake "popping".

Speaking of unintelligible gibberish all that data about the airplanes engines. What's the point of that none of those engines have reversers this plane did not have reverse but you suggested they use it. you're the one who's making wild ass comments.

You don't seem to understand that when you have, "Problems" with the brakes & everything goes to shit because of brake issues, it's generaly called "Popping the Brakes" ie, he popped the brakes coming in.

Popping Noise When Braking.

Worn-out or rotor discs, loose and worn-out brake pads, and distorted brake backing plates are common causes of popping noise while braking.

In addition, incorrectly adjusted brakes, contaminated brake fluid, and strange objects trapped in brakes can be to blame.

After a period, the rotor’s protective coating will get warped, resulting in a popping or squeaking sound. The noises may be produced louder by severely damaged discs.

The next cause of rotor surface deflection is letting your rotors be exposed to cold water while they are still hot.

It causes the surface to distort, and you will hear an exact popping noise & even vibration.

The popping noise when braking is caused by a loose brake pad and the brake disc rubbing on your pads. It can also be other interior elements vibrating around.

Once you notice a loud popping noise, it’s possible that one of your backing plates has been bent or distorted.

It also leads to wonky wear on the brake pads, triggering premature malfunction or overheating accumulation inside of them. Moreover, it causes them to break and make sounds when it’s used.

Brake fluid, or hygroscopic fluid, can absorb the air’s moisture and induce the brake pads to start locking up.

It may end up with a popping sound when brake fluid becomes polluted, the brake pads and the rotor could be frozen.

This sound occurs due to the friction created whenever the component rubs against the rotors and brake pads.

The highlighted section shows that given the circumstances where there was water on the tarmac & the brakes were heating up, that the brake system "Popped" & warped because the heat of the brakes reacted with the cold water & they warped because of this & resulted in failure & ultimately the death of an individual.

Opening sentence of my original post.
'I would say that he popped the brakes in the wet conditions".

Highlighted from Above : The next cause of rotor surface deflection is letting your rotors be exposed to cold water while they are still hot.

Furthermore, you don't seem to understand that the nonscientific term used for this scenario, is called "Popping the Brakes" or he / she / they, "Popped the Brakes" & with all your experience in aviation, I find it very hard to understand why you haven't heard this phrase before, EVER I might add !

[Hogmann]

Originally Posted by Roosta ↗

You don't seem to understand that when you have, "Problems" with the brakes & everything goes to shit because of brake issues, it's generaly called "Popping the Brakes" ie, he popped the brakes coming in.

Nope never heard of it and can't find that on the internet anywhere. I have heard popping the brakes used to reference throwing out Speed Brakes in flight.
And everything you described is examples of poor maintenance or improper use. I don't see anything that describes brake failure because you use them to their limit. Which was your original statement of what popping the brakes is.

But all that aside this accident was clearly caused by trying to land on a Runway that was not nearly long enough. Not brake failure or as you say "popping".