Night offshore landings: a new approach?

[DOUBLE BOGEY]

Night Approaches

He All,

Thanks to all of you who have requested a copy of the presentation.

I think I have managed to send you all a copy as requested. If there are any stragglers who still would like please PM me.

Thank you to those of you who have written back with your comments. I simple have not had time to respond to you all personally.

The interim AAIB report has been released. The reccomendations are not great. Completely miss the point of the "Required Visual References" for the final descent and landing.

CAA are on the case though and hopefully we will see some progress.

DB

[Lt.Fubar]

Originally Posted by [URL="http://www.pprune.org/members/161920-double-bogey"

DOUBLE BOGEY[/url]]I agree, but I have heard that it very difficult to produce a robust system that is omnidiractional. Also what about moving decks???

On the contrary it is very easy, although someone have to pay for it first.

For example, few minutes in CAD produces such simplified sketch:



It's a simple design incorporating 3 light sources - in this case LED arrays, that cover 360° , and their visibility is blocked by those "plates" between, all inside polycarbonate transparent shell. Simple, cheap and don't weight much (mostly empty inside) - size dependent on the light source.

Depends what you need, you can change the design very easily. For example in this one, crew on approach will see the yellow light when at angle between -5 to +15, then green from +15 to +25, and red form +25 to +60. The angles can be easily changed, can be overlapping, or not.

For moving decks - mount it on two axis gimbals with electric servos, put gyro inside, and electronics that will steer the servos by gyro input. Small company could design and put into production such system in a week or two

Although that design is not very size-efficient, the best way to do this would be with Fresnel lenses instead of plates, that way the size could be limited by at least 70%... but they're not cheap.

[JimL]

As I posted before, we fitted and trialled the Omni-direction Approach Path Indicator (ODAPI) on the Leman 'A' in the Southern North Sea in the early 90s.

The main issue was the lack of initial visual pickup because the beam was swamped by the ambient lighting. It might be better now because more powerful LEDs could be used. It was also a mechanical device (rotating mirrors I think); if built now, phased arrays might be used reducing the size and and mechanical complexity - it also needed a power supply.

There is also the issue of siting; to be omnidirectional it ought to be sited at the centre of the deck but that is somewhat impractical. The beam should also permit flight down the beam to the deck (with a threshold crossing height) but that would require siting above the deck level (or behind for a single azimuth approach) and still would not fit in with offshore performance profiles.

All-in-all a positive report was filed but the device was returned until problems had been solved. Flying constant angle curved approaches was good handling practice. Most pilots did not think it had much merit.

Jim

[Lt.Fubar]

In context of this topic, that kind of "ODAPI" would be used to 'pinpoint' the CTB, and guide for the most of the way - near the helipad where the guide path have increased error, there would be enough reference points to make a safe touchdown without looking at the device. On aircraft carriers the "meatball" is also useles when over the deck.

The LEDs may be very powerful these days. Look at the LED Beacons - those are single 40W LEDs, in such device you could fit tens or hundreds of 20-50W ones - it would be seen for miles, and could be actually blinding if looked at when on the deck (would probably need a power regulating circuit that would dim the lights after dark).

If there still would be a problem to pinpoint the location of the device on oil rig, it could also have a strobe, or the light itself could blink. As for power supply... that's no problem on the oil rig or a ship.

The presentation is very interesting and informative, I took liberty of providing it to pilots I know who fly to the rigs, and don't visit this forum. Although the main problem is of deterring "how fat, the 'fat egg' should be". Therefore an omni-directional system would give an definite answer to that - without guesing, see the green light = your on the glidepath.

[JimL]

I like the logic of your argument - I had come to the same conclusion; best to forget flying all the way down the beam (although it would be possible for a proportion of the final descent), the essence is only to establish the intercept, the initial descent path and hence the correct 'sight picture'.

There are pointers to the difficulties that could exist; for years we have been trying to provide a wave-off light (to avoid the problem of wrong-rig landings) - we could never find one with sufficient intensity that it would be noticed when the pilot had convinced himself that this was the correct rig.

Don't minimise the problem of power supply - this has to be an intrinsically safe device.

You cannot rely on the lights being dimmed on the rig - some platforms are the equivalent of small cities and the lighting is there for a reason; dimming will not happen and can't be relied upon - best to strive for intensity.

The siting would also be problematic as it would be masked if approaching from the Limited Obstacle Sector.

However:

It is probably time to revisit the basis for the ODAPI; the advent of powerful LED lighting has now probably changed the balance.

Finding the correct angle of approach just from the deck lights is not really that simple. As I indicated in an earlier post, when measured, the ones shown on the presentation were: 10 degrees for too low; 20 degreees; and 35 degrees for too high. So not as easy as it first appears!

An alternative solution (to establishing the point of final descent) would be with a waypoint on the GPS; this could be calculated geometrically using (say) a 6 degree angle, the centre of the helideck and the altitude on the final track to fix it.

Jim

[ambidextrous]

onmi-directional approach aid

Lt.Fubar,
Sorry to be a 'wet blanket' re. your idea of using LED's. I ran my own idea of an ODAPI utilising LED's past Richard Walker some three years ago. Richard Walker, inventor of the "Firefly ODAPI", first trialled some twenty years ago & utilising gyros and mirrors opined that powerful LED's would be prone to 'scatter' thus giving inaccurate glidescope indications and glare!
However, don't let me put you off.
with fraternal greetings,
ambi
PS: Your assertion that a company could put such an instrument into production in a week or two is open to question I think.

[Lt.Fubar]

The power supply isn't really a major problem, you can incorporate into the design a set of battery's that would be constantly charged, when the power is available, and would be used when gone - providing power for XX hours. It's a matter of design criteria. Others for example would be - the operating temperatures (it would need a heating unit to work in freezing conditions). Intensity of lights at given distance. number of lights, their angles, angles of overlapping (if needed) etc. etc.

The lights dimming would be for the device itself, not for the platform, as you can produce some insane amount of light with todays LED arrays. With enough units, you can make it brighter than your landing lights. The high intensity LEDs usually produce light in 110° cone - in this case, the led would be visible on 110° horizontal, and given focused amount in vertical. Let's say a the glidepath would be 10° wide - you can easily focus it that way using a lense. So, using an ring array, with 24 LEDs, in any given moment there would be 7 hi-power LEDs visible to you, more if more rings is used... so, look at the modern strobes, and imagine that such ODAPI device would look to you as 24 such lights at once, non-stop. That's a lot of light.

Using GPS or radar return to deterring the CTB can be also used, although I thinks its application and accuracy depends heavily on the crew, as they have to prepare in advance the data they need. I think it could work as a start, but not very good for the long run. An ODAPI type device, or omni-directional ILS system (could be done, though much more complicated and costly) would be more useful.

Ambidextrous - Yes the glare might be bit of a problem, but not much. But it's all academics, if no one will take time to try and build a test system using today's technology.

[malabo]

Problem on rig landings has always been one of speed control. Stable approach allows the pilot now visual with the rig to give the correct amount of nose up pitch to achieve the steady deceleration and loaded disk required to end up at a hover over a deck suspended in mid-air. Incidentally, that is also the problem with trying to aim too far away from the deck in the latter part of the approach before deciding on committed - hard to do looking at the deck, even harder looking at thin air.

I doubt that we are actually flying a constant angle, but we'll know soon enough as we start to spend money experimenting with the technology of angle guidance. Virtually all pilots I've flown with that are not trying some OEI-obsessed profile will fly reasonable slope and decelerating approaches, just like we teach them. Start them back a reasonable distance like 1-2 miles, and start some kind of deceleration to a point with a reasonable slope to the deck (maybe around 1/2 mile?) and its all going to work out for you. Now you transition to a gradual descent all the while decelerating. Minor corrections are done in the final phase by looking at the shape of the deck.

As far as flying a profile flat on an ARA because of a low ceiling, well what of it? Seems like a normal day in the life of a helicopter pilot - adapting a profile to meet an operational requirement, normally introduced in the first third of a CPL course. The reason the ARA's for the past 40 years have not been a problem in this regard is because they were "set-up" a ways back, and stabilized with respect to speed. I don't see any justification in Bogey's presentation for raising the MDH on an ARA at all.

I've read the extensive (almost defensively so) credentials of the proponents of this new approach, but in the course of their argument I find it difficult to be convinced that they understand offshore approaches any better than anyone else.

Hope I don't sound too much like Swamp76.........

[Flying Bull]

Hi Lt. Fubar,

when consindering to build your device, I suggest you to contact
LED LENSER - Professionelle, fokussierbare LED-Taschenlampen von Zweibrueder Optoelectronics
for the LED-part.
Nowadays the LEDs produced by them are brighter than the bulbs from tactical torches....
Got i.e. the T7 torch which has a laserwarning on it - so smal but so bright that you throw your other torches away!
Zweibrueder has a development department, which is always interested in new ideas.

Greetings Flying Bull

[DOUBLE BOGEY]

Malabo

MALABO,

I am dumbfounded by your last post.

You apear (quite correctly in my view) to identify the critical issues of speed control (speed stability) and Pitch Attitude during a night or ARA approach.

However, in refusing to consider my call for raising the MDH (at night only) to Deck + 200 feet, you seem to think that stable airspeed and minimum nose pitch up attitudes can both be achieved when 50 feet above the deck and very close to it.

Just to be clear, the interim AAIB report on the 225 inadvertent ditching states that the crew were too low to see the helideck lights and the crew felt they were "too close to the installation" and the nose was raised to slow down (20+ degrees) , ROD built up (-1000 fpm) , airpeed decayed (<35 KIAS) and the helicopter hit the sea.

This situation is clasically synonymous with being below the ideal (Deck + 200 Feet) MDH/CTB intersect line whilst trying to keep stable until the CTB is reached.

MALABO - I assume the slight about credentials was aimed at me and that is your right to freedom of speech.

Heres mine - YOU ARE EITHER THICK AS PIG-DO-DO or a Manager.

LIGHTING SYSTEM.

I like the idea of any kind of imporvement but my personal experience of Night Approaches both from an Operational and Instructional point of view is that "Capturing" the CTB slope is not generally problematic provided you are operating in acceptable WX conditions.

Its the bit before the CTB where these approaches seem to go wrong.

[mario139]

DB,
Thanks for the thread and a very pertinent discussion. We are grappling with exactly this issue at the bottom of the world right now. One option we are considering / trialling is a constant groundspeed approach. The (hoped for) advantage is two-fold:
1. Constant ground speed means (on a given night), constant IAS, which means constant pitch attitude. I.e. the sight picture is fixed in the windshield. All that remains is for the pilot to hold the same glidepath with collective until reaching that point of full visual cues where the final transition to the hover is made.
2. Constant ground-speed means ROD is always the same for a given approach angle.

We are trialling 30 kts, with a commence descent at 500 feet, 1.0 nm. Sounds a little flat but actually is not too bad. Our aim point (target height) is 50 feet above the deck, and you do the math from there (ROD is about 200 fpm). I've flown it in nil wind which is probably the most difficult, and the helicopter is nice and stable and the approach easy to control. As wind increases, it gets easier.

The big problem I see with the classic decelerative approach is that everything is changing on that approach. The airspeed is decreasing (which requires a steady increase in pitch attitude so your visual cue is moving); power required increases, so collective input is necessary. This gives flapback so cyclic correction is required. The whole approach is very dynamic (aka unstable!), which is possibly why it is very difficult to make a good job of it first time up for a couple of months.

Be interested in feedback on this concept.

Cheers

[Burr Styers]

Night Deck landings

Reading this thread with interest. Have done the offshore thing N Sea, Single pilot night ops, shuttling etc. Now working in flight safety. One thing that you may want to consider in evaluating approaches to installations, irrespective of time of day, is your companys Flight data monitoring programme (FDM), or for those across the pond FOQA.

This will have objective data about approaches to offshore installations, and with todays interprative software, it would be very easy to see what profiles are actually being flown, versus pilots recollections of what they thought they flew - usually two different things.

This should be an area rich in data that could be used in a constuctive way, to benefit the safety, particularly of night ops to a helideck, which I think those who have done this will agree, is the most demanding discipline that you have to master.

I think those organisations that have a helicopter FDM programme, and conduct night operations, might wish to consider some depth analysis (if they haven't already) of what is actually being flown.

It could well be that what it finds, concurs with what is trained/SOP. It could also thorugh up some interesting material.

I suggest this, as nobody else on the thread has mentioned it yet, nor does it seem to have much currency in the helicopter forum - which is a bit suprising.

My three penneth

BS

[JimL]

Mario,

That is a 3 degree slope with a rate of descent of 175ft/min (using the North Sea mean deck height of 98ft plus 50ft); at 500ft, 30kts in still wind, you will be at the back-side of the drag curve with a difficult sight picture (the deck almost looks flat at 3 degrees).

Try doubling your approach angle.

Not sure what is wrong with the normal sight picture approach; keeping a constant speed will always start the procedure too slow and could end it too fast.

Jim

[DOUBLE BOGEY]

EXTRACT FROM AIIB BULLETIN INTO 225 CRASH

Since the accident, the operator has amended the procedures in its Operations Manual for offshore night operations.
For night visual approaches Stable Approach Configuration (SAC) criteria have been specified.
They are to be met by a Visual Gate Point, 2 nm from the destination installation or vessel.

In addition:
‘if at any time after the Visual Gate Point visual contact with the installation/vessel is lost or becomes uncertain, a Go-around is mandatory.’

I am left utterly speechless that the combined brains of the AAIB and the CAA think that the above is sufficient to prevent a further re-occurence of the incident.

The above singularly fails:

TO RECOGNISE THE DIFFERENCE BETWEEN THE MAPT AND THE FDP/CTB

TO MANDATE LEVEL FLIGHT AT MDH FROM THE MAPT TO THE FDP/CTB

TO ADDRESS AT ALL THE INADEQUATE AMO0UNT OF SPACE ABOVE THE DECK PRESENTED BY AN MDH (ARA) OF DECK + 50 FEET

TO ADDRESS AT ALL THE REQUIREMENT FOR A PROPER, MANDATED, PUBLISHED PROFILE - LEADING TO PUBLISHED MANDATORY INTERVENTION PARAMETERS AND POLICIES without which the NHP is as much use as a chocolate fireguard, left to rely only on his common sense, experience and ever the victim of the severity of the cockpit gradient.

COME ON AIIB & CAA If thats the best you can do I need a TAX rebate!!!


I have sent the presnetation to about 600 people worldwide from all companies, agencies, safety organsiation and training orgainistaions.

I have not had one negative response and the general trend has been "Why has this not been done already"

If the combined planet sized brains of the AAIB and CAA result in the above reccomendations then god help us all.


Fingers out guys before we have another one!!!!

[JimL]

DB,

Stop shouting at us.

This is text for the establishment of the Visual Gate Point and clarification on the necessity for a go-around; you don't know what it also says in the Operations Manual. It might already say:

• At night, there shall be no en-route descent to VFR unless the cloud base has been reported and forecast to be above 1,200ft.
• At night, for a VFR approach there shall be no manoeuvring below 500ft until adequate visual reference has been achieved.
• At night for shuttling, the en-route height shall not be below 500ft
• At night for shuttling the en-route visibility shall be reported and forecast to be above 5km.

Here are some other points -for a visual approach: there is no MDH; there is no MAPt; there are no such terms such as FDP or CBT.

The excerpts from the Bond Operations Manual are just that - they cannot be construed as recommendations from the CAA or the AAIB; the CAA are in no position to give recommendations because the AAIB has not yet reported.

As a matter of interest, the helideck elevation is reported to be 166ft.

Jim

[Lt.Fubar]

Originally Posted by JimL

Mario,

That is a 3 degree slope with a rate of descent of 175ft/min (using the North Sea mean deck height of 98ft plus 50ft); at 500ft, 30kts in still wind, you will be at the back-side of the drag curve with a difficult sight picture (the deck almost looks flat at 3 degrees).

Try doubling your approach angle.

The military is using 3° glide slope, although, it is assisted by SGSI, TACAN DME, ship and aircraft radar. Plus, to make the SGSI light more visible all other lights are dimmed when helicopter is on approach, and until above the deck, landing site is not crew concern.

[DOUBLE BOGEY]

JimL,

The entire point to this debate is whether there should be such a practice as NIGHT VISUAL APPROACHES.

My argument, from the outset, is this practice should cease.

All night approaches should be conducted as monitored Instrument approaches, through the MAPT, to the FDP/CTB.

I accept that at present there is no formal recognition of the FDP/CTB.

The crux to the stability and therefore the safety of the approach is that there should be recognition of this theoretical and then physical point in space, and build the profile around it, and the MAPT.

Just because these things do not exist at present it does not mean they should not be invented.

I accept that many of you in the industry have been working on this subject for many years. Guess what....the solutions that have been implied by the current regulations and guidance do not work properly. This incident, and many others like it are the physical manefestations of failings in the past to recognise, once and for all, that night VMC over the sea simply does not exist.

The solution I have proposed works. Very well. It is safe, controlled and easy to mandate to implement.

The principles which it employs, that taken together to produce a complete profile, work regardless of the weather experienced during the approach. This is the key to preventing poor decision making due to slant range visibility during the initial descent leaving the crew "stranded" trying to execute some kind of VMC procedure.

I said from the outset that the proposal is radical. It is. It abandons some archaic presumptions which in my view are a throwback to the time when full IFR monitored procedures were something of a novelty.

For the most part, we now have equipment that if operated correctly, removes majority of the "Human Element" to night approaches and this is the key, just as it is during and ILS or NDB.

The fundemental chanllenge is to get the industry and the regulators to swallow the simple fact that being 50 feet above the deck (in extremis), when the wx is poor, is a nigh on impossible ask of a large transport helicopter. Increasing this margin is in my view a major step forward, not only providing the dynamics for a stable approach, but inherently improving the safety of such approaches.

DB

[Spheriflex]

???

Just wondering why it is so quiet from the main land Europe......

Maybe the wheel was allready invented!

Night time: minimum 300' or deck height + 100' whichever is higher only with gs < 70kts. And lots more of usefull stuff.
Spheriflex.

[dipperm0]

In the French Navy, night VFR approach on a ship or deck is prohibited. Whatever the helo is ( from Super Frelon to Alouette III) and whatever the ship is ( from aircraft carrier down to fishing boat or sailing yacht) the let down starts at 2500 yards / 500 ft with passage by 2000/400- 1500/300 down to 1000 yards 200 ft. Speed is between 60 to 80 knots at the beginning, descelerating during descent toward 40 + wind at 1000 yds / 200 ft.

Durind the initial descent Both pilots are under instruments and non flying pilot report radar distances.

At 200 ft, flying pilot raises his eyes and look for visual references while non flying pilot remains head down, and starts reporting repeatedly radio altimeter height, ground speed and distance until instructed by flying pilot to stop. If at 800 yards, visual is gained, descent is resumed. If not, missed approach procedure is flown by non flying pilot.

Below 200 ft, non flying pilot puts his hands around ( without touching) flight controls and is ready to take the controls and apply the missed approach procedure if requested to do so by the flying pilot. Usual missed approach procedure is left turn 30 deg from approach course, takeoff power and Vy.

If it could help..

D0

[Vespertine]

Hey DB

Hope my message got through, would love a copy.

cheers