Did this pilot "know something"?

It was also pretty warm yesterday. What was the density altitude?

Finally a pilot who takes serious the weight and balance calculations…

Lanzarote airport is obstacle limited in one runway direction, if I remember right to the northeast. I am quite sure that this was the reason. Normally, take off is to the side where there are no obstacles, but if wind conditions make it necessary to take off on the obstacle limited runway, you are severely take off weight limited due to a hill in the departure path.

In the “old days” most pilots went around this limitation by briefing a “early right turn in VMC” if they had an engine failure,but of course to my knowledge nobody ever did need to resort to this. In the days of flight data monitoring however, things like this are history. You could of course take less fuel and go for a fuel stop somewhere in between as well, but very few airlines will do that. Easier to kick pax off and pay them a ticket with someone else.

Yes, much less to do with the field length and more to do with the obstacles on climb out from RW03. The worst wind for us is anything that gives low teens knots of headwind, becuase it’s not enough to help the performance, but it’s enough to preclude taking off with a tailwind on RW21 (we have a 10kt tailwind limit).

For passenger weights, we use 88kg for male, 70kg for female and 35kg for children. This includes hand carry on baggage. Our hold baggage is weighed and we use an exact weight, although if we get a last minute addition/subtraction of hold baggage, it assumes it is the average weight of bag from the original load (calculated obviously from knowing how many pieces of baggage and what the total weight is).

FWIW, our normal method of dealing with weight issues in Lanzarote is to look at reducing the fuel on board through various (proper) means, then to tech stop somewhere, typically Faro LPFR, rather than offload people and/or bags.

Lanzarote is indeed a place that is performance restricted most of the times.
A different flap setting didn’t work because flap 5 was the sweet spot for both climb and runway limits.
Runway 21 was a big delay most of the times
We mostly did a pack-off takeoff to get some extra performance.
Never had it come that far that i needed a tech stop.

Pirho wrote:

For passenger weights, we use 88kg for male, 70kg for female and 35kg for children. This includes hand carry on baggage.

Wow. These are pretty close to the old “Iata” weights I last saw when I started in 1986….

Pirho wrote:

FWIW, our normal method of dealing with weight issues in Lanzarote is to look at reducing the fuel on board through various (proper) means,

The gotcha I’ve seen a few times is that the wind was within limits and so they fuelled up… only then to become out of limits and staying there. De-fuelling is almost never an option.

But I wonder, the normal hacking order would be to offload baggage before passengers. (and cargo/mail before that).

Peter wrote:

Normally, I am told, they fly with a standard allowance of say 120kg per passenger and luggage

This is the pre-flight planning weight and last I heard it’s 100 kgs in most airlines. 100 pax = 10 tons. You need a pre-flight EZFW in order to start your flight calculations. 100 kgs is pretty accurate for most destinations. Most planning systems do have the possibility to adjust that per destination, so if you know that one destination has high baggage loads (e.g. foreign worker flights which have notoriously high baggage loads as well as above average quota of males) you can adjust it to the long term average. Some airline specific systems build statistics on this and will then use planning weights according to statistical average.

This usually works quite well as I remember. Hardly ever you get massive changes from EZFW to actual ZFW but if you do, sometimes quite drastical measures are necessary.

Peter wrote:

Doesn’t the 2400m runway work favourably re obstacle clearance, or aren’t you allowed to consider that?

Today this is all Ipad territory but generally it works like this:

RTOW is the smallest of 3:
Structural MTOW
Runway lenght limited RTOW
Obstacle limited RTOW

In the case of Lanzarote, Runway 03 is always obstacle limited due to a hill in the departure path. So the runway lenght is hardly ever a factor. On 21, you are normally runway lenght limited or up to MTOW.

Those obstacle limitedd weights are usually calculated based on OEI performance after engine failure at V1.
Runway limitations take into account both OEI and accelerate-stop distances as well as other factors.

Both of those will also be modified for technical irreguliarities, such as brakes (Anti Skid), engine de-rate or flight control irregularities just to mention a few. (E.g. the MD11 had a way to use the ailerons as additional flaps, without that, you’d loose a couple of tons of RTOW or if anti skid is inop, accelerate stop distance is longer and therefore you loose weight, e.t.c. )

We used to have so called Individual Runway Tables, where you would go in with temperature and wind and could read out the RTOW plus V-Speeds at a glance. Today you enter all the factors in your Ipad and it will come up with the figures.

Additionally those tables will also give you indications on how to “Flex” the engine, if you have weight to spare on longer runways so you can de-rate your engine performance and still get a safe take off.

Peter wrote:

The plane should be airborne around halfway.

Normally it is somewhere there particularly in 2 engined airplanes, but you often get take offs which use most of the runway lenght available. It is a function of ASDA (Accelerate-Stop-Distance) and one engine out performance which determines the RTOW on runway lenght basis. In some cases you are also able to calculate stop ways and other surfaces into that calculation which are usually not part of the runway lenght available, so you end up with take offs which do pretty exactly the required obstacle clearance height at the runway end, which usually is 50 ft.

Peter wrote:

Also curious that the pilots did not realise this until shortly before takeoff.

Several scenarios where this can happen. Most often, conditions are ok for 21 and look like they stay that way, so the crew fuels up for the return leg. And then when you are ready to start up, you notice, that it’s gone off limits for 21 due to increased tail wind or other unexpected changes. De-fuelling is not an option (as it takes for ever) so you can end up in a quagmire where you have to reduce load in other ways. It does not happen too often so that pax will notice, but cargo guys can sing a song or five about this.

What they apparently did wrong is assuming and planning for RW21 – or their software did it for them… They understood the situation a bit late, once plane was full and ready.
Another possibility is a bet on fuel price. I suppose jet is more expensive on a portuguese island than on their base of Liverpool, because for tushc flight (Lanzarote to liverpool), I think roughly 8 tones of jet is needed, vs 20 tons max on a320 I think, they maybe started the previous leg full fuel to avoid refuelling at lanzarote… may be wrong…