In UK, helicopters operating from field sites seldom, if ever, "pick up a IFR flight plan". Most operate on an ad hoc basis, outside of controlled airspace, using lower airspace radar service where available (and there are significant gaps in the latter). There is no requirement to file an IFR flight plan when operating in Class G and no such thing as a clearance to operate within it. Most lower airspace in overland UK is Class G apart from airways, control areas, CTRs, and ATZs/MATZs. Basically, pilots manage their own departure and climb to MSA and pick up whatever en route ATC service they can glean. When requesting a radar service in Class G, controllers will generally advise that they can offer only a limited radar service.

In over fifteen years of corporate RW aviation, I've only ever filed one IFR flight plan prior to flight and that was almost fifteen years ago, simply because the captain decided to try it from a major airport to another minor one. In practice, we never got to fly any of the planned route and were messed about so badly we became concerned about our fuel state.

Crab,

It may shatter your World View but that translated quite easily into Spam....perhaps it might prove difficult for those who are limited to a single "dialect" but that post came across plain as Day.

Ah, but you've been well trained SAS:ok:

The RFM surely is a result of testing by manufacturer test-pilots?
If there was sufficient commercial pressure from operators saying they wanted to perform IMC hover takeoffs, then they would presumably test the helo under these conditions and approve a profile?
I can only assume that the profile is not there because there has not been the overt demand for it.

You know what happens when you "assume"!

I'm not going to get beaten with that hosepipe again?

Shy
Thanks for bringing this CAA Safety Notice up. Overall I must say I think it is a good effort from the CAA, particularly as it is for guidance. As you say too, important that they clearly accept private site IMC departures. Whilst I'm with Crab (and probably you) that 0/0 departures are not a problem given training and a good AFCS, the issues ref Vmini in the RFM are valid and achieving Vmini is a much easier departure technique. One thing I would say ref their criteria for establishing suitable AOM, is the loading of the acft, which was not mentioned. Ultimately it is all about acceleration, and there is a huge difference in a mid weight acft, which may achieve Vmini in 250m, and one at MTOW when well over twice that may be required, with a much lower climb gradient subsequently.

Non-PCPlod - the Vmini will be mainly due to the inacuracies of thec pitot.static system since very few give IAS below 40 or so kts with any reliability and some airspeed tapes dont have any figures below 30 kts.

Since that speed is required to fly the aircraft accurately (notwithstanding what a good AP is allowed to do using other sensors), it is no surprise that they don't test or certify it in the low speed instrument regime.

It's not that the aircraft can't do it because we all know they can but no-one is going to risk the litigation when someone spears one in flying in cloud at 30 kts by saying it is safe to do so.

Shy
Thanks for bringing this CAA Safety Notice up. Overall I must say I think it is a good effort from the CAA, particularly as it is for guidance. As you say too, important that they clearly accept private site IMC departures. Whilst I'm with Crab (and probably you) that 0/0 departures are not a problem given training and a good AFCS, the issues ref Vmini in the RFM are valid and achieving Vmini is a much easier departure technique. One thing I would say ref their criteria for establishing suitable AOM, is the loading of the acft, which was not mentioned. Ultimately it is all about acceleration, and there is a huge difference in a mid weight acft, which may achieve Vmini in 250m, and one at MTOW when well over twice that may be required, with a much lower climb gradient subsequently.

rotorspeed, couldn't agree more. The Emmental lines up very quickly with 'it's in my tool bag' ... 'I was shown this once 3 years ago' .... instructors should be explaining this guidance to the pilot to allow him to challenge the customer, negotiate the payload deduction, point out lack of experience, refuse the flight - as they also say they have been brave enough to do, on their posts on this site.

Crab-
If they certify the SAR modes so that you can do a TU from the hover, it has kind of been proven that it is both possible and safe (if you have this phase of the software). Therefore, the Vmini should not be an issue. It kind of seems pointless having a TU mode if you can't use it IMC - e.g. at night over the oggin.

The SAR modes will use other sensors (GPS, accelerometers, inertial nav, even doppler) to give the speed which is why they are allowed to control TU/TD at low speed.

If the aircraft had a low speed display (LVI or groundspeed on the PFD/ND) then it could be used by the pilot for low speed IF but whether such 'extras' would be specified during the certification process I don't know.

Exactly - which kind of makes the VMini a strange restriction if you have the other kit.
139s all display groundspeed, and provide a "hover display" as an HSI option, to show low speed vector (both direction and speed)

Yes, perhaps it should be 'Vmini when hand flown' or similar - it's all a bit of a nonsense.

Hello Gents!

I am an average SARpilot (currently flying with AW139) and doing my best to follow your discussion. Just curious: how would You describe a SAFE 0/0 takeoff with coupled modes? Any suggestions?

No knowledge of the 139, but I assume there is Force Trim, Heading Hold, Attitude Hold, and the ability to Trim the Attitude Datum while the Pilot can control power setting via the Collective position?

Sadly Crab the rules for certification are not that accommodating.

Come on Geoff, I know you can explain this ;)

I was just wondering if there is a procedure (published or not) which guarantees either safe landing or flyaway during 0/0 takeoff?

Is there a guarantee for such for any takeoff if one includes all contingencies?

Aviation is based upon accepting reasonable risks is it not?

Consider the 225 situation extant!

Thanks for your kind reminder! "Guarantees" was not an optimum word. Point taken ;) And of course there are risks involved, even if you
are flying Cat A profiles... On the other hand the RFM describes e.g. how to use RHT/HOV and TU-modes...

Search&Rescue,
How do you do it?

You are talking/asking about takeoff techniques? Describe takeoff/landing site and WX conditions. Even if I am flying SAR, we do have WX restrictions...

Horizontal departure - from hover engage TU and once past min if speed (50/60kts) engage ALTA.
Vertical departure - from auto hover (30ft) increase collective height bug to suitable height (500ft for example). At safe height to clear obstacles increase hover position forward to 60 kts then follow ALTA as above.

The basic 139 has autohover and therefore a vertical departure can be followed as above which I guess was an option for LABL. Practice using auto modes is essential if you intend to fly in such conditions.

If you refer to a similar concept of " safely" continuing the "0/0" type take off as commonly used in other prescribed and approved techniques.....it would be determined more by performance capability considering a failed engine at any point in the take off and the height of obstacles in the take off path.

Such take offs are very rare...excepting night offshore and article or desert operations.

The technique I learned was to ascend "vertically" using a "hover" attitude....until clear of known obstacles the adjust the pitch attitude to achieve Vbroc until 500feet AGL then use the desired airspeed/ROC/power setting desired.

Mind you we were doing these in UH-1's, H-19's, H-34's....single engine helicopters....two of which had Manual throttles.

So continued flight post Engine Failure was easy decision!

Consider in this accident....the visibility (lack of....) prevented a safe takeoff using any approved takeoff profile. The right profile was no take off under the circumstances.

Perhaps the U.K. Rules need examining!

Thanks Jeepys! Good advice! 👍

We have a quite flat country, so it will be the horizontal dep most of the times. Maybe I would start with "Confined profile" in order to reject easily if needed and @TDPe select TU. The Vertical dep might be a good option sometimes (e.g. due to poor references), but I guess that you have to plan some kind "commitment point" anyway in case of OEI before 500 ft or what would you do in case of OEI at 350 ft? Just "Standard Flyaway" and Vtoss climb until clear of obstacles or?

In auto hover mode, will the 139 hands free maintain its position solidly over the ground and not drift without any corrective input?

The HOV mode is pretty accurate. We use the HOV mode e.g. during 30-320 ft hover when checking the hoistcables (primary/secondary) with max 270kg weight and the helo will hold the position usually ± 1-2m.

Depends how strong and sudden the gusts of wind are. But generally speaking - yep!

Is the HOV mode input accelerometer/FOG or GPS/FMS based or combination of sources? Sorry for the ' works great and lasts a long time ' question.

Yes the auto hover in the 139 is very good. GPS held and often well within the 1-2m.

S&R,
If you are working to a high TDPe of say 300ft in poor weather and vis then I think first you have to ask the question 'do we really need to do this'? If the answer is yes as it can be in the SAR theatre then you have two options if you have an engine failure prior to TDP when doing a vertical procedure. You either keep the helicopter coupled in hov and fly the collective in the descent back to the pad or continue with the OEI profile post TDP.

That makes sense! Never tried, but I will x-check the procedure in Sim next time... Thanks again! 👍

Which sim? What phase does it refelct?


Which 139: which phase does it have. What options were included/switched on/off?


The upper mode buttons may be there (or not), but whether the aircraft you are in will do the things promised here is another matter.

The crew of G-LBAL didn't make use of a sophisticed AFCS apparently (or MCC or CRM for that matter). Perhaps because the aircraft they were flying didn't have these options or because the working environment wasn't conducive to training and development.

Think the thread reached broad conclusion that their work environment was risky and that to fly was the wrong decision a while ago. Rehashing how they might have done it better is surely not the right way to go.

I disagree Torque. I have gleaned much critical knowledge from this website over the past 15 years or so. If any discussion here provides any kind of community wide education which may help to prevent another accident, then I'm all for it. I truly appreciate the wealth of knowledge that surfaces here. There are many different ways of operating, and I'd like to review as many as possible to select for my armory. I will admit though that threads can become a little incestuous from the same band of posters. I'd like to see the Pprune of old return, where more folks are encouraged to post without the fear of being shot down by the regulars. Back to the 'new church on the block' instead of the old boys club that Pprune seems to have morphed in to.

Sir Korsky

Thanks for your engouragement! 👍

The AW139 Hover Mode does NOT hold a GPS or FMS position. It is a velocity reference. If you have selected "0 velocity" and you drift (such as due to cross wind) it does not return you to the original position.

These discussions providing only partially correct information is what gets people in trouble when they "think" they know the system.

Very true HLCPTR, but it's certainly up to the individual to pick the flowers in the minefield.

HLCPTR

Very good point! 👍 Direct from RFM/Suppl 69: "The HOV mode utilizes the AHRS ground velocities to maintain hover or low speed flying".

All correct, but it is VERY good at maintaining a position, even in a crosswind.

Not to condone or criticize the actions of this crew since I have no knowledge of what pressures they were faced with, but if they would have used the full capabilities of the automation of the 139 a departure in near 0/0 could have been successfully accomplished.
Again, not suggesting that anyone should ever attempt this except maybe in a life and death situation.