Question for mil pilots: DIY IFR approach legality in emergencies?

[paradoxbox]

I was reading a book called Viper Pilot and at one point in the book, the author talks about an enormous sandstorm wrecking visibility at all nearby airfields. The tankers flew off to alternates and were too far to provide refueling and his entire flight was in an emergency fuel state. The only alternates not engulfed by the sandstorm were beyond their max range at their fuel state.

In the book, he describes flying a dry run over a runway while he still had enough visibility (I think it was about 1/2 mile at that point), and he set a steerpoint over the runway as he flew and sent the steerpoint to his flight via the link. He then did a pattern and landed, with the visibility dropping to something like 1/4 or 1/8th of a mile. The whole flight landed safely by following the DIY approach.

So, this technique actually works quite well and probably saved the flight. I tried it in the Falcon BMS sim and it worked a lot better than I expected.

But what is the legality of this in the military? Would you be in doo-doo for allowing your fuel state to get so low? And how does the military react to this kind of DIY instrument approach if conducted in an emergency like as described?

[just another jocky]

I suspect, in your example, the pilots would have been congratulated for saving $$$m in combat aircraft but investigated as to why they were in that situation in the first place.

[PPRuNeUser0211]

Paradox,

In my fleet (military) we routinely train to carry out such an approach using internal aids. It's not 'legal' as such, so we don't carry it out IMC live flying for training. The key point is that military flying in an operational context has a lot of variables that are not as easily controlled as in a peacetime context and a lot of your 'options' can be pulled from under you pretty quickly.

The procedure we use is fairly similar to the one described. If the airfield has a published approach we'll always try and mimick that in the kit, but if it doesn't I can have a look at the map, have a best guess and design what is effectively an RNAV/ point in space approach on the fly.

Our chain of command would certainly have no issue with us doing the above if there was no option, though there would hopefully be a review process after the fact to understand why we were forced into it and to try and prevent it happening again.

[[email protected]]

it comes firmly under the heading of Emergency Let Down - not something you would do in normal circumstances (except to train for it VFR as pba says) but available in extremis as a far better alternative to running out of fuel.

Having said that, we are moving towards precision based nav and more GPS-based approaches.

[Fareastdriver]

In the forties there used to be a piece of kit in Air Traffic called a 'Porka'. This was a miniature motar and would fire a flare vertically when required.

Should the airfield be socked in with fog then an aircraft would get steers to the airfield at 1,000ft. Just before he reached the overhead they would fire the Porka so that the pilot would see where the tower was. He would pass it and carry out a timed circuit: Rate one turn/one minute/descending Rate one turn, that hopefully would have him on finals at 2/300 ft. in a position to see the runway.

They were out of date when I started but we were still taught timed circuits. Seemed to work OK.

[[email protected]]

In the forties there used to be a piece of kit in Air Traffic called a 'Porka'. the modern version is the WRAF assistant but spelled with an er at the end:E

DF homing to the overhead was always available if the instrument approaches weren't available and the same concept was used for emergency letdowns in the AAC where the troops on the ground would listen out for the aircraft in the overhead and transmit to the aircraft - a timed turn teardrop procedure would then be executed to let down to the 'overhead' on a 'safe' heading. Not very precise but it could work well if the terrain was suitable.

[MPN11]

Never heard of the Porka ... YLSNED

DF could be a good get-you-down provided that the antenna was in a decent position relative to the runway. However, the brick blockhouse was usually well offset to the side, so a straight homing to the antenna would put you on the grass. I did try, in my intensive DF days at Strubby, of doing an inbound homing on a very slightly offset heading, and then kicking off the angle when the pilot called [on request] Outer Marker which was on the coast a bit south of Mablethorpe. In theory that had him roughly on the centreline with 3.5 miles to run. Safe enough over the flatlands of the Lincolnshire coast, but far from an exact science!

We did a lot of time-related procedures back then, which is why the Approach Controller was always equipped with a pair of HM Stopwatches - as indeed was Local where a DF display was fitted.

[gums]

Salute!

Plenty of ways for successful do-it-yourself approaches unless the vis/ceiling is like a hundred and a quarter or 200 and a half.

The old ways used DF by tower and your own radio gear ( flew two jets with DF radios, and one was fielded in 1971, plus had better avionics than the original F-16I I flew 8 years later),

The use of the inertial/GPS nav gear plus a good ground map radar makes a non-precision approch fairly easy, even if not practiced. In Thailand during one of the monsoon seasons, the haze was so bad we could not see the field from 1500 feet and 4 or 5 miles. So we used radar and nav gear to align with the rwy for an overhead pattern.

With the HUD in the Sluf and Viper you set tgt elevation, so your tgt "box" ( TD symbol) is very good. Can update position using the radar. So now you can have a symbol at the end of the runway and the correct elevation. We used this to start descending 100 miles out and simply placed our flight path marker over the box. Duhhhh.

So Dan had to enter the position of the field that had not already been entered as a destination. We used to "mark" the ramp or end of rwy at home base to use later, or we could manually enter the coords. So getting an accurate pos for a "strange" field using a flyby nav update seems a good idea. Can use radar to get the TD box there and then refine the coords with the overfly nav update.

The Sluf had that magic map, so you could refine your nav position using radar, then designate your destination on the map to get the TD box and steering.

Gums sends...

[Two's in]

Remembering of course, that there is always enough fuel during an emergency let down to get you to the accident site.

[Tiger_mate]

Helicopters:

1970's.
Decca moving map - very dodgy but works for supertankers.

1980's.
TANS (Tactical Air Navigation System) used Dopplar cross refer TANS to a radio beacon and update 'FIX' (DME/TACAN) in the overhead, followed by a set pattern to parallel the runway outbound at 1.5nm offset to begin a turn in at 7nm from the threshold. Pretty much an SRE talkdown but internally from the crewman.

1990's Super TANS / RNS252 (Racal nav system) - similar to above but GPS input replaces dopplar. GPS less likely to go walk about than dopplar was. FIX could be offset as long as TANS and other radio aid agreed with one another. Pattern was the same downwind at 1500'agl IIRC.

Deep doo doo:
Radar Altimeter monitored let-down ideally over the sea. Wind farms and gas/oil rigs make this very iffy.

and/or
Establish hover on the Rad Alt at a pre determined height and get crewman to open the door and look down - why? - because slant vis (pilot) is not as good as vertically down (crewman); and this procedure may just prevent you wearing a wires necklace in the event of high tension wires being nearby.

Practised all of the above weekly and used it once:- In Belize after Radar (SRE) piped up "Loss of radar contact due to radar clutter (weather)" just at the time when we needed ATC more than ever and options were few if any. In fairness we were already halfway down the approach at 3nm+ when this event occurred. The rain was so heavy that having the wipers on was a wasted effort. On an ILS/PAR/SRE the TANS/GPS was always set up to act as a back-up.

[ShyTorque]

1980's.
TANS (Tactical Air Navigation System) used Dopplar cross refer TANS to a radio beacon and update 'FIX' (DME/TACAN) in the overhead, followed by a set pattern to parallel the runway outbound at 1.5nm offset to begin a turn in at 7nm from the threshold. Pretty much an SRE talkdown but internally from the crewman.

Not forgetting the good old Decca let down (without the moving map). I never really understood how it was done, but thankfully most of the crewmen did!

[[email protected]]

Apart from the one who decided to offset one lane to the left to allow for the crosswind:ok:

[Floppy Link]

And the one over the sea who confused the depth contours and the Decca lanes...

[Dominator2]

I recall that in the Tornado F3 we had an MDA in the Release To Service for Internal Aids Approaches using the Radar and Main Computer position. IAAs were practiced IMC on normal training sorties. They were normally monitored by ATC but not sure if that was a legal requirement?

Many moons ago before the days of "rules for everything" we used to perform a self navigated QGH pattern using Rebecca/Ureka in the Jet Provost. I cannot remember what minimums we used; about 1000ft I think?

[Mogwi]

In the '80s the SHAR had an internal aids let-down that worked very well; lock mother with the cloth co*k, enter the flying course and select PIA (pilot interpreted approach); the HUD then gave centreline and glidepath together with cues for hover-stop and braking-stop to get you alongside in the hover. Only snag was flying a very unstable jet at 140kts with 60 nozzles. I forget what the official limits were but it was proven down to 200' on occaisions, when flying non-div. Sorted the men etc!

Off to practise my turn-backs.

[Fareastdriver]

Out in the Solomon Islands we had a GPS letdown.. We didn't have the full kit to do approaches, all we could do was similar to an NDB. This was necessary because of the weather and terrain we had to fly over the top of cloud covered mountains and let down the other side. The Chinese registered aircraft I had flown turned the beam bar automatically when a new track came up but the Bristow cheapies did not.

A case in point was the approach to Kwaimbaambaala. This was a 'airstrip. that was the other side of a mountain with an approach from the northwest. One had to go over the top of the mountain at around 6,000 and let down the other side and do a GPS approach.

The GPS would track you on base leg directly back at the mountain you had just crossed. You would sit there following it with your radar gradually turning red as it filled up with rocks. You would keep ranging it down fully depressed and even at 2.5 nm, it was painting at the top. The steer bar would twitch as you came on the approach track and you would input a screaming max rate turn to the left through 120 degrees and reset the beam bar so that you recovered to the centre line pointing away from the hills.

When you broke cloud you were then reminded how big and how close the hills were on the right hand side.

The things you do for money.

[SASless]

"Loss of radar contact due to radar clutter (weather)" just at the time when we needed ATC more than ever and options were few if any


In Vietnam War Years....using Army operated GCA sites for "Radar Navigation and Approaches"....during Monsoon Season the dreaded words..."Radar Contact lost...Resume own navigation!" were a certainty upon being in solid cloud...much less Monsoon Rains.

I always wondered what method they thought we would use upon being told that as there might generally was not an operable Nav Receiver aboard any of the Helicopters.....assuming the NDB's might be working....which they usually were not.

[MPN11]

Very interesting hearing all these 'cockpit perspectives' for getting down. I though ATC was indispensable, but clearly not :)

[NutLoose]

In the forties there used to be a piece of kit in Air Traffic called a 'Porka'. This was a miniature motar and would fire a flare vertically when required.

Should the airfield be socked in with fog then an aircraft would get steers to the airfield at 1,000ft. Just before he reached the overhead they would fire the Porka so that the pilot would see where the tower was. He would pass it and carry out a timed circuit: Rate one turn/one minute/descending Rate one turn, that hopefully would have him on finals at 2/300 ft. in a position to see the runway.

They were out of date when I started but we were still taught timed circuits. Seemed to work OK.

Still in existence, had a discussion about them a while back when I was on gardening leave, :E as someone was asking what they were, various ones are still dotted around the Country, this one is in the New Forest

Metal socket behind the concrete Airfield pundit code - identified as a Signal Mortar. Photo taken August 2013. (http://www.newforestheritage.org/image/847/)

And this one at Beaulieu

WWII Hampshire - RAF Beaulieu airfield:... (C) Mike Searle :: Geograph Britain and Ireland (http://www.geograph.org.uk/photo/5348972)

http://www.geograph.org.uk/photo/5312611



http://www.newforestheritage.org/uploads/images/large/847.JPG

[Yellow Sun]

I find it surprising that no one has mentioned the internal aids approaches that we used to carry out on the V Force. It is entirely possible that these were also carried out earlier on other types equipped with H2S. Maybe someone could confirm this?

YS

[[email protected]]

I though ATC was indispensable, but clearly not ATC aka the Flying Prevention Branch:)

[MPN11]

ATC aka the Flying Prevention Branch:)As indeed what I said when I was introduced to HRH Prince Andrew, when he enquired what I did. I was given the 'crossed fingers to deflect a curse' and a big grin ;)

[gums]

Salute!

We may have some Aussies here that flew in 'nam those early years, and they can add to my comment. Her Majesty would not allow our Brit exchange pilots to deploy with us when our unit went there.

My first tour in 67/68 had almost zero "traffic control". The CRC's ( combat/control reporting center - Paddy, Peacock, Paris, Pyramid, etc.) provided advisories and tracked us if we used a specific squawk. We would get with the nearest one and tell them our mission number, planned altitude and provide altitude updates, but mostly did our own navigation. They could help, but we did most of it. The CRC would advise us of altitude and route conflicts, but nothing like stateside ATC at the time. They also coordinated with approach control and the control agency or whatever at our destination/target.

There was virtually no civilian traffic except a few airliners at the big airfields.

They had good connections with the military command centers and would coordinate changes to our mission, plus tell fields we were inbound with an emergency or fuel divert. Think "real" ATC type control.

By the end of 1972 we were getting to "ATC" type stuff with the CRC's- assigned altitudes and such. If not on a combat mission we had to file an ICAO flight plan at the tower.

By 1975 on my last tour it was like stateside, with training areas and low level routes and so forth.

Oh well, we innovated, improvised and overcame. But the early years required good airmanship and DIY approaches on many occasions.

Gums recalls...

[paradoxbox]

Interesting posts guys.

What kind of precautions do you take for obstacle or terrain management if you're in this kind of scenario? Do you fly a steeper approach than usual or just go for it normally?

I think in the book author's case, there was limited ATC available (No radar IIRC). I suppose the F16 can use its A2G radar to locate obstacles on the glide path. Mountains probably not much of an issue in that particular region of the world. If I remember correctly, because it was a sandstorm there was no "cloud base" so they flew it right to the runway with minimal visibility all the way down. Sounds like fun for practice but not so fun after finishing a long and tiring mission.

[FL235]

Of course, you may have to do it all yourself, and rely on local knowledge.. Came back to Kiriwina, Trobriand Is., once from a photo run way out to the east to find a heavy, but heavy, rainstorm sitting over the airtrip. Well, that's what you have island reserve for, so started orbiting the island, no point going anywhere else as the only fuel was at Kiriwina. An hour later things were getting interesting as the storm showed no sign of moving or abating. We could see the island outside the storm, so forming a mental map of the tracks near the strip I picked a point on the track nearest to the strip to start a turn to the strip heading. Points in my favour - nothing higher than a palm tree in the area, and a B29 strip made with coronous surface. May flood, but never gets soft or slippery and 10,000 Ft long by 300 ft wide (from memory) So run in at 100 ft., on strip heading, look down on both sides, check we could both see cones going past, set the DG accurately, go back into the clear, wheels and flaps down, do it again. Cones established, close throttles and hold heading. Absolutely nil forward vis in the rain. And then there was the time coming into POM when the tower advised that a storm would beat me to it. Storm coming from the west, me from the east. Bootless Bay marker, B17 wreck still visible, a dead heat at the outer marker aerial. But there's a service track from the strip to that installation, flat ground. So tuck that track under the side window at about 30 ft. and wait for the tarmac to show up. Call from the tower "Where are you?" "Ön the ground, on the strip" "That's good, can't see you, strip's closed". The good old days?

[Fareastdriver]

On the Island of Unst the airstrip was enlarged to support the Shetland Basin oilfield. There were no aids apart from an NDB on the coast 1 nm east of the runway.

The trick when it socked in with low cloud etc was to fly from the platforms descending to 200 ft approaching the coast. Homing on to the NDB carefully dodging around a couple of small islands brought you to the installation, sometimes at 50 ft/50 yds.

Continued flight was easy. You followed the excavator marks where they had laid the cable from the corner of the apron to the beacon.

You can still see it on Google Earth.

[gums]

Salute!

Some really good techniques for the newbies here.

For home field, pay attention to all the landmarks off the end of the runway.

Looking over the side to see a familiar barn or house or intersection or whatever might be the only way to "update" your internal nav system no matter what your aircraft nav system says.

I made many landings in heavy snow and it was nice to see a red barn about 3/4 mile on final.

Gums recalls...

[binbrook]

No-one has mentioned extending the trailing aerial.

[Dominator2]

Another IFR approach that had debatable clearance was the Trails GCA. In both the Phantom F4 and Tornado F3 it was common place for a formation to use their AI radar to follow the leader whilst he performed a GCA. We flew up to 4 aircraft at 1nm spacing down the approach with cloudbase as low as 200ft.

With a good GCA controller, as soon as the 1st aircaft called visual, the talkdown switched to the next in the stream and so on. It was a very efficient way to recover 4 aircraft quickly, although could be fraught with difficulty.

If ILS were available it was much easier as a Trails ILS put all of the control in the cockpit. For Combat Ready crews the workload was quite manageable.

[Ascend Charlie]

In desperation, set your GPS to the aerodrome reference point, set the inbound track to be the most into-wind runway, and let yourself down gently - you might end up in the aerial farm, or if lucky, offset from the runway, but in a chopper you could be slow enough to get away with it.

[nipva]

In both the Phantom F4 and Tornado F3 it was common place for a formation to use their AI radar to follow the leader whilst he performed a GCA

I feel that I ought to point out on behalf of the WIWOLs here that this procedure was an SOP in the Lightning force well before the advent of the F4 and Tornado F3 albeit for pairs only. I doubt that any authorisers would condone launching a 4-ship with Y2/Amber forecast bearing in mind the Lightning's paucity of fuel.

[nipva]

There is of course the other 'internal aids' approach as demonstrated by Puddy Catt one day when recovering his Hunter (no internal aids apart from DME) to Brawdy in typical low cloud conditions. When told by ATC that the colour state was Y2 and asked what type of instrument recovery he would like, responded in his inimitable fashion 'the weather's far too bad for an instrument recovery dear boy, I shall be recovering visually'.

[Dominator2]

nipva,

In your day ATC could recover aircraft a 3nm spacing. By 1990 due to "skill fade" they seemed to need 6-7 nm which normally ended up at 8-9nm! A Long stream with 4 ac to land. We also flew Pairs Tied but not normally when the X wind was above 20kts.

[SpazSinbad]

First visual approach method in IFR conditions one learnt in the olden daze hopelessly non-instrumented Vampires and Sea Venoms was this one (words from another Venom pilot before the end in 1971). I did a few of these myself but none so dramatic as described thusly: (lots of details omitted to protect innocent) :}
"...Another GCA, below bingo fuel, lost us again.... hand signalled to wingman we would do the old Venom let down. DR'd out to sea, climbed to 5000, let down on the pressure alt to 1000', then onto the radio alt till visual (about 100'), left turn onto 270, reached the coast around Crookhaven, up the coast to the Shoalhaven River, down the river to Pig Island, onto 213°. To stay visual we were down to roof tops over the town, eased over the golf course and plonked down on the numbers r/w21...." [fuel must have been nada]

[ShyTorque]

In the event of an airborne emergency it's not a top priority to consider what the legal team might have to say afterwards....it's more about doing what needs to be done to save the aircraft with you in it.

Would anyone consider a Martin Baker letdown "legal" but an "ad-hoc" approach that brought the aircraft safely back not so?

Some military "jobs" in my distant past were often done IMC and almost always without radar cover (in fact we did what we could to avoid being seen on radar). ATC closed at midnight so there was no SRA available on our return in the early hours (and we had no ILS equipment fitted). I won't go into detail into what we needed to do to let down but it worked.

I never even considered what the legal opposition might have had to say about it.

[MPN11]

Have done a few trails GCAs in the distant past ... quite stimulating for the controller(s). Didn't work too well with Aussie Mirages, though, as their AI was some sort of harmonic of the PAR frequency, leading to quite severe jamming of the PAR picture!

[MPN11]

And ..l ShyTorque mentions the 'legal' aspects. There was a Lightning that overshot a GCA on a VERY claggy day, and with minimal fuel. REALLY minimal. He staggered around the circuit at 'stupid feet agl', found the runway again and landed.

AOC 11 Gp had several of his staff investigating the various legalities of IFR flight in the visual circuit, within a MATZ, unauthorised low-flying etc. etc. I know it was 'several' because when I called someone (IFS?) they said "What's up? This is the third call I've had today about this!" ISTR AOC let the topic drop after numerous 1v1 conversations with the staff involved ... it was too difficult!

If you consider the VFR criteria, a vast amount of circuit flying is technically IFR ;)

[MACH2NUMBER]

During Op Deny Flight, F3 navs sometimes used the handheld GPS to monitor ATC instructions. We also tried approaches using runway heading and height for specific distances called by the nav. Seemed to work OK, but would have used it for real only in extremis.

[MPN11]

Pre-planning options for in extremis sounds very sensible to me. :ok:

We all tend these days to rely on so much technical wizardry in our daily lives, without a lot of thought about what would happen if it wasn't there.

I don't have a stock of candles, but I certainly have a few flashlights [and batteries!].

[CharlieJuliet]

I recall many long gone occasions with talkdown telling me to look ahead at 200 ft, but then keep talking as often the cloudbase was well below that, and we needed extra help to get in. ISTR one Christmas in RAFG getting airborne on Christmas Eve with a poor forecast and (we were mudmovers) trying to do PI s with 3 aircraft - not very successfully!! I was glad to get the Bruggen recall as weather was going down. V impressed with my Nav as he stayed with me all the way (specially as the previous evening had been the Xmas Draw!!)although vis was close to 0 - I would have not been so trusting! However, we both made Christmas at home that year.

[Fareastdriver]

On the North Sea the procedure for ILSs was that the PF (Pilot Flying) would fly it to the ILS decision point and then call "Decide." At that point the PNF (Pilot Not Flying) would confirm that he had the runway visual, would take over control and land the aeroplane.

On 'difficult' days the call was;

Deeeeeeeeeecccccccccccccccccccccciiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiidddddddddddddddddddde.

[Dundiggin']

On helicopters any crewman worth his salt would have a basic Decca (old days) or GPS Tans template ready for any diversion or IFR type let down to anywhere relevant to the sortie.

The basic letdown would commence 5 miles from the TDP allowing for a 3 degree per mile letdown starting at 1500', 5 miles out, 300' per mile descent. Height adjustments would be made to the template to take in Ht of TDP and adjustment made to get QFE from RPS. If no RPS then QFE worked out using map contours.. Those Ht adjustments were then added to template hts for 3 degree approach.

Plot position of aircraft, work out heading to start point say about 7 miles out, plot final approach heading (into wind with a bit of luck).

Position aircraft about 7 miles out, adjust for wind and begin letdown at 5 mile point using modified hts. This used to work beautifully for me in every case except for one day when the Decca lanes went tonto and we were 1.5 miles rt of track. :uhoh: 'twas a Decca problem not mine - honest! Bloody Decca thank God for GPS!

Crewmen were expected to demonstrate this procedure on check rides.:cool:

[Shackman]

Ahhh.. the Decca Letdown with the 3 degree glidepath was actually a relatively easy approach to fly, so long as it was more or less into wind; but beware the pitfalls of being one lane out. Recovering to Manston from a job with a cloudbase somewhere near the deck we were shooting the usual Decca approach (Manston had no aids available at this time) all was going well until I saw a red light come out of the murk at the same height. A rapid application of power took us just over the cooling towers of Richborough Power Station - now long gone - at which point the Nav apologised for being one lane left of track!

Of note we also practiced a similar self radar let down in the MR Shackleton using the ASV 21 radar, which in the hands of most of the operators could 'see' a runway and give us a distance talk down. The only problem was we had to be visual by about 400 ft so as to lower the undercarriage before touchdown (this action immediately raised the retractable radome, and thus halted the talkdown).

[Exmil]

Many years ago, down south, we were airborne as a single F4 from MPA. Wx forecast was white, prob grn, tempo ylo in showers. We pulled up over west Falkland half way through the sortie to check the wx and discovered it was red in a zero viz blizzard that wasn't moving. No AAR was available so we endured until it became obvious we were going to have to do some proper crew work as the approach aids wouldn't get us to a legal decision height (200 ft for rating) at which we could see the runway. Having been crewed together for a while and both having been there a few times we set the radalt to 100 ft and did an IAA - the radar was good enough to pick up some features. Nothing seen - reset to 50 ft. Nothing seen, reset to 30 ft. Still nothing seen. Radalt at 20 ft and knowing what the obstructions were and being able to see the threshold above us on the radar we came up the (very slight) valley from the west. We agreed first to see a light shouts "light". One flashed past the stbd tip so we dumped it on the deck. We had to wait for someone to walk out in front of the "follow me" landy feeling for the lights with their boots because viz was 10-20ft. Can't recall who the auth was; all we got were a few looks from the rest of the guys along the lines of "ballsy, but you walked away from it". Groundcrew commented "I'm surprised you didn't flame out - there is no fuel in this jet". Don't remember anyone saying either "you broke the rules" or "well done". Still remember thinking "you know; we're pretty good".

[Darvan]

On both the Vulcan and Buccaneer the navigator was authorised to provide an Internal Aids service to the pilot by conducting an ATC-style talk down to the appropriate airfield MDH. With skill, the talk down could be as accurate as a PAR at a familiar airfield where the runway threshold could be identified with accuracy on the H2S or Blue Parrot (i.e. Waddington or Lossiemouth). I am pretty sure an Internal Aids was also in the RtoA for a GR1 and is currently permitted for the GR4.