Zero-zero takeoff (also low visibility takeoff)

Peter wrote:

So there is no 400m absolute minimum for departures after all?

That doesn’t follow. It is common that the pilot is called upon to assess conditions, it doesn’t have to be assessed by a third party.

I would do all of it, including specific approval.

SIM – yes, aircraft – that could be tricky.

I wouldn’t allow single engine aircraft at less than 400m because of the no-option, engine failure option.

Training, standard MEP engine failure stuff, particularly engine failure on the ground. I would also cover instrument failure etc.

Provision of RVR – basically I read that as you can use pilot assessment for the first third but must have RVR for the middle and end segments. I could be wrong.

Currency – pretty much the same way we used to do the 90 day pax rule (I’m not saying 90 days would be the yardstick).

What am I really saying? I’m saying that I think sub-400m is territory that should be discouraged.

Timothy wrote:

In the UK we would not say that an IFR departure is only possible with an official instrument departure.

It’s not related to SID (that’s why I wrote “instrument departure” rather than SID) but it’s related to official type of operation allowed at particular airport. If IFR is not specified as allowed type of operations then only VFR departures are allowed. So you can say whatever you want in UK but you’re aware that regulation in this case is pretty accurate.

And we would not say that a departure in IMC is under VFR. It is under the IFR; that’s seems fairly obvious.

The situation here is pretty obvious – it’s not allowed to depart from VFR only airport in IMC, so legally it can’t be IFR.

Emir wrote:

The situation here is pretty obvious – it’s not allowed to depart from VFR only airport in IMC, so legally it can’t be IFR.

What about a farmer’s field, or your back garden (for a helicopter)?

I, like Peter, have done a few takeoffs under the hood and found them surprisingly easy….I suspect though, if faced with a pea-souper, it would not be so easy to throttle up into the nothingness…but the risk (in a SE) probably has less to do with running off the runway and more to do with being able to put it down in the event of engine failure…

Dave_Phillips wrote:

I wouldn’t allow single engine aircraft at less than 400m because of the no-option, engine failure option.

What about single engine aircraft where it is SOP to pull the parachute in case of an engine failure? Would you exempt those, or would that be “collateral damage” to your attempt at a rule definition? How about SET, would you still judge the risk of engine failure high enough to warrant a general rule prohibiting take-offs for everyone?

I think Timothy had it earlier.

All of these arguments are completely useless without backup, they are essentially expression of emotions around risk.

Any empirical risk assessment could rely on 40 years of evidence of accidents if that kind of operation posed a real risk. That the regulators and nobody here can do that is very telling.

Moreover, then you would have to ban takeoffs in OVC001, VV000 and RVR of 500 meters as well. No way to land reasonably safely in these conditions after an engine failure just after crossing the fence…

So yes, in order to cater for the very different conditions (runway type, surroundings, AC type, etc) one would need to have a rather low legal minimum and then have faith that pilots will exercise good judgement and possibly – in certain cases – will decide To stay on the ground, even if conditions are above legal minimums. Some will say this works fine in practice, other will say it doesn’t work. We can go around in circles with this.

AnthonyQ wrote:

if faced with a pea-souper

This is the problem. Those of us old enough and London enough to remember pea-soupers know that that meant that you could not see the width of the pavement, let alone the width of the road. To take off in a pea-souper would only really be as an alternative to some other dire outcome, such as being surrounded by Daesh.

But the numbers we are talking about here, between 175m and 400m are a very different matter. On the roads, a visibility of 300m is disconcerting, but you would consider it be more like mist than fog.

If you have a number of aids, both visual and electronic, taking off in 2-300m is really not that much of a challenge, even taking failure modes into account.