Q Codes & Let Downs 1950s

[KN647]

Can anyone out there explain the following please. This was an RAF Dakota flying from Entebbe to RAF Eastleigh. I could not find QDH on the web and does anyone know what the 'Safety lane Details' to Eastleigh were?
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At 1715Z the aircraft contacted Eastleigh and gave an ETA of 1732Z, 11,500 ft IFR.
Two minutes later Eastleigh asked the pilot if he could see the lights of Nairobi and on receiving a negative reply instructed the pilot to maintain height and passed him the safety lane details.
Shortly afterwards the pilot reported that he could see the lights of Nairobi. He was instructed to hold his height and was given the safety lane direction. Seven minutes from ETA the Controller gave the pilot “clear to descend QDH 085º.
The pilot acknowledged this call. About five minutes later the aircraft was again called.
A reply was received strength three but fading. At this time a large flash was seen in the direction of the Ngong Hills.[/FONT][/SIZE]

Any help or advice would be much appreciated.

NICK

[Been Accounting]

Magnetic bearing from station.

See Wikipedia Q code

[Old-Duffer]

Just to add to the above, there were seven souls on board and all were killed. The date was June 1954 and the weather was described on the Accident Card as 'poor'. The aircraft belonged to Malta Comms Flt.

Old Duffer

[spekesoftly]

The aircraft was apparently seen seen to crash to the West or WSW of the Airport (Ngong Hills), so I suggest QDH should read QDM 085 (Magnetic heading to the station).

[Whopity]

CAP1 / AP1529 1945 Edition:
QDH - What is causing the present interference? The present interference is caused by....
QFH - May I descend below the Clouds? You may descend below the Clouds
QGH - May I land using the procedure of Descent through Cloud? You may land using the procedure of Descent through Cloud
I suggest that QDH is a misprint for QDM.

[Warmtoast]

should read QDM 085 (Magnetic heading to the station).

Agree

From someone who spent the first few years of his life in the early 1950's as a national serviceman VHF/DF operator at RAF Thornhill (5 FTS), S. Rhodesia. See below.

http://i145.photobucket.com/albums/r231/thawes/RAF%20Thornhill/ThornhillVHFDFHomerExterior.jpg

http://i145.photobucket.com/albums/r231/thawes/RAF%20Thornhill/ThornhillVHFDFHomerInterior.jpg

http://i145.photobucket.com/albums/r231/thawes/RAF%20Thornhill/ThornhillAtthewheel.jpg

[BOAC]

CDTC approaches (Controlled Descent Through Cloud) began the overhead and followed a large teardrop pattern. The 'Safety Lane' is probably the relevant track to follow out and in. This approach system was still in use in the late 60's.

[stopbar]

As an ATCO I was doing them mid 70's at Cranwell/Barkston Heath

[Warmtoast]

Ref my post #6 above.

Following from my training notes.


Direction Finding (DF)

The aeronautical stations that offer a VHF Direction Finding (VDF) service are listed in the UK AIP AD. Some VDF stations stipulate that the service is not available for enroute navigation purposes (except in emergency). VDF bearing information will only be given when conditions are satisfactory and radio bearings fall within calibrated limits of the station. If the provision of a radio bearing is not possible the pilot will be told of the reason.

A pilot may request a bearing or heading using the appropriate phrase or Q code to specify the service required. Each aircraft transmission shall be ended by the aircraft call sign.

A VDF station will provide the following as requested:

1. QDR – Magnetic bearing of the aircraft from the station (i.e. ..... Approach G-ABCD request QDR G-ABCD).
2. QDM – Magnetic heading to be steered by the aircraft (assuming no wind) to reach the VDF station (i.e. ..... Approach G-ABCD request QDM G-ABCD).
3. QTE – True bearing of the aircraft from the station (i.e. ..... Approach G-ABCD request True Bearing (or QTE) G-ABCD).

The direction-finding station will reply in the following manner:

1. The appropriate phrase or Q code.
2. The bearing or heading in degrees in relation to the direction finding station.
3. The class of bearing.
4. The time of observation, if necessary.

The accuracy of the observation is classified as follows:
• Class A – Accurate within plus or minus 2 degrees
• Class B – Accurate within plus or minus 5 degrees
• Class C – Accurate within plus or minus 10 degrees
• Class D – Accuracy less than Class C
NOTE: Normally no better than Class B bearing will be available.

QGH (Controlled Descent Through Cloud) Procedure

QGH letdowns may be provided, when requested by a pilot, at aerodromes where the procedure is approved. The procedure provides for control of an aircraft from its initial approach level to a position, from which an approach can be completed visually, approach may not be aligned with a runway.

On receiving a request for a QGH the aircraft is to be homed overhead the VDF aerial at or descending to the lowest available flight level/altitude taking into account the minimum safe flight level or safety altitude as appropriate. During homing the following message will be passed to the pilot:

During the procedure aircraft replies are used to obtain D/F bearings. Pilots may be asked to make additional transmissions for D/F. With some equipment the full callsign is sufficient to obtain bearings.

Two D/F indications are required to confirm the aircraft is overhead the VDF aerial; then instructions are given to achieve the desired outbound track.

On completion of the overhead turn and when bearings indicate the aircraft is outbound the controller starts timing the outbound leg and provides heading corrections derived from a series of bearings to make good the desired outbound track. Descent instructions and the appropriate pressure setting are also given during this procedure.

On completion of the timed outbound leg (e.g. 3 min) the aircraft is instructed to turn onto a heading to achieve the final approach track.
When the aircraft reports steady on completion of the inbound turn, headings will continue to be given to achieve the inbound track. During the inbound leg the controller will pass instructions to be followed in the event of a missed approach (Note: At military airfields the weather and missed approach procedure may be passed at an earlier stage in the procedure). Descent clearance to minimum descent height and the QFE will be given on this leg.

If the pilot has not reported ‘visual’ by the time minimum descent height is reached he may be instructed to maintain level flight until he is overhead the VDF. If the aircraft is not ‘visual’ when overhead the VDF, the controller will give the instruction to carry out a missed approach procedure.


The following appeared in "BUKA" the RAF Thornhill station magazine in 1952:


BUKA December, 1952

THORNHILL HOMER
By L.A.C. J. VINE

Thornhill has its own legion of “forgotten men,” so it would appear. A frustrated band of individuals, forsaken and abandoned—hibernating on the extremities of the airfield.

Few people know they exist, but these “few” realise only too well the loneliness of braving the elements of a winter’s night, or the humidity of being cooped up on a summer’s evening.

The forsaken men—six R/T. D/F. Operators, The place—the camp’s Homer Station, one mile from Air Traffic Control on the far side of the main runway.

From early morn until late at night these isolated beings keep up a continuous watch Their function to pass directional bearings requested by aircraft enabling pilots to pin-point their positions: and in cases of distress to bring them home safely.

Last year the total number of bearings passed by these operators was 35,903, and an RAF record of 2,810 bearings in ten days, was set up. A place of prominence is given to a commendation from the last Signals Officer on this fine standard.

A conical shaped, black and white chequered hut, with what seems to be two television masts poking through the roof, is how the Homer appears to the layman. Recently the building was uprooted and moved even farther away from civilisation. But inside a far from melancholy air prevails, and many an amusing incident helps to break the monotony of the day.

WILD LIFE
All kinds of rodents, lizards and bees pester the life of the occupants. Some months ago, by chance, a swarm of bees settled around the aerial platform of the Homer roof, on the old site. During a particularly hot day the swarm descended into the building and the “ship” was quickly abandoned with sorely-stung airmen springing in all directions. Fire Section beekeeper F./Sgt. Dare was hurriedly called in to exorcise the pests so work could continue.

Another story of woe told me, happened during the summer. A very perspiring operator decided to strip down to the waist, and with his feet firmly positioned on the table, a cloud of smoke circling about his head, he settled down with a derogatory magazine at band. Minutes later, the Group Signals Officer’s head appeared around the door—even now the airman’s face glows red each time the door is flung open.

But the job of manning the Homer is done well and efficiently. Thornhill being a master diversion airfield in this part of Rhodesia, civilian aircraft use our Homer facility quite extensively. Twice a week the BOAC Comet gives a call, on its run between Johannesburg and Livingstone.

OPERATOR BITES THE DUST
Before the recent upheaval the “ancient” Homer’s position was in close proximity to the airfield’s main runway. Planes frequently barely scraped over the aerials, and a wave from pilot to operator was always good to boost trembling morale, at those times. However, the standing leg-pull is the thy one mistrusting operator leapt for his life through the observation hatchway on seeing an Anson, due to wind-drift, heading straight for the building.

Tall, fair wavy haired Cpl. Dave Pearce keeps an eye on the proceedings, but the staff of “big-dip” operators is “Stinkie” Hill, “Arny” Arnold, “Dad” Stephens, “Prof” Hawes, and the latest arrival, “Ginger” Burgoyne.
So, if you’re ever that far off course, drop in and witness these “gen” boys working their fine array of technical equipment.

[BOAC]

As an ATCO I was doing them mid 70's at Cranwell/Barkston Heath - in that case you will have 'served' me. The best I had was a student's mask failure, when I said 'for a bit of fun, let's do a 'real' speechless QGH'.

"blip blip blp blip"

"Speechless a/c calling Cranwell take the callsign Speechless 1. Is this a practice?"

"Blip Blip"

SILENCE

"Speechless 1, we cannot accept you at Cranditzl"

I eventually managed to stop laughing :ok:

[BEagle]

Me too, I guess!

Many a 'CDTC' and 'FODTC' in my logbook.... "Call passing headings" etc., followed by some visual manoeuvring to join the PFL pattern. Controllers were very adept at this procedure and had our every confidence.

Of course back in those days the RAF still had sufficient aeroplanes to keep controllers in practice.....:(

[Fox3WheresMyBanana]

QGH still being taught in 1985. I had one speechless practice which became a real speechless. We (dual) thought it would just confuse everyone to declare an emergency that was the same as the practice, so (as it was a nice day) simply landed off it.

[ShyTorque]

QGH letdowns were still being provided at RAF Newton (a non radar equipped, all grass airfield) in the 1990s. Also being carried out were "back bearing" instrument departures. The locally based aircraft had no navaids whatsoever (prior to the later cockpit upgrade) but pilots were expected to carry out instrument departures, operate on instructional sorties above 8/8 cloud, then recover to base on instruments. When in and above cloud, position fixes were obtained via the use of "true bearings" from Newton Approach ATC and either Cranwell or Waddington.

[KN647]

Thank you for that explanation - there were a few more typos in the document that I got from the MOD and it all make sense now.

Anything on 'Safety Path'?

My father was radio operator on the flight from Malta.
The captains wife was my mothers best friend up until the day she died.

Thank you, NICK

[Whopity]

The Safety Path would have been a specific Magnetic Track leading to the airfield. Quite probably 085 degrees, over the city. This track would have been surveyed for obstacles and the aircraft cleared down to appropriate heights when the VDF bearing indicated the aircraft was in the safety lane. The Runway track at Eastleigh is approximately 060 degrees,and the position of the Ngong Hills to the North of the extended centreline for RW06. Such a safety lane would be to allow the aircraft to descend North of the hills whilst converging with the centreline. If the aircraft had drifted right out of the safety lane, it could easily have made contact with the hills.

[BOAC]

Anything on 'Safety Path'? - where does this expression come from? I told you in post #7 what the Safety LANE was . What is the safety PATH and what in particular do you want to know about it?

[KN647]

'was given the safety lane direction'

Is there any difference between the two?
I was just quoting from the report that I was sent by the MOD.

[KN647]

Ahhhh Rhodesia. I also spent time in Rhodesia, but in the 1970s. What a great county it was. What a shame that it has been ruined by a minority to the detriment of the majority.

[BOAC]

Is there any difference between the two?
I was just quoting from the report that I was sent by the MOD. - absolutely no idea, but unless you post the report we cannot say.

[KN647]

The only part of the report that mentions 'safety lane direction' has been posted at the top of this thread. The rest of the report that was released to me only contains names and information not relevant to the questions that I was asking. I was hoping that someone with some knowledge of the let down into Eastleigh would respond. Anyway thank you for your help.

[BOAC]

The confusion is why you are asking about a 'Safety Path' when all you have posted refers to a 'Safety Lane'.- which has been explained Why have you introduced this expression? If we knew, perhaps we could help?

[Downwind.Maddl-Land]

As an ex-QGH (aka CDTC) endorsed Approach Controller – as I recall - the Safety Height (all approaches were on QFE remember ) ‘steps’ were:
Homing: Lowest High-level Quadrantal Flight Level (circa FL120 or thereabouts), Lowest Safe Quadrantal Flight Level (below FL120) or lowest procedure safety height (if starting below transition altitude).

Overhead – at least 2 no-bearings or very rapidly changing QDMs – then sending ‘Bloggs’ outbound on the required outbound track (+/- 15º ‘oversteer’ if track change was greater than 90º). Set QFE, NO DESCENT YET.

Outbound: Descent outbound to Intermediate Approach Height (IAH) could not be commenced until the outbound QDM was within +/- 60º of the outbound track. Then descent to IAH was initiated. Turn inbound was commenced at ½ Overhead height + 2,000ft (Hi level procedures) or timed (3 or 4 mins for lo-level procedures) when turn inbound to Final Approach Track (FAT) commenced. (For all old ATCO’s – ‘double any outbound QDM error and apply it in the same direction’ for the inbound steer!)

Inbound: Descent below IAH to Procedure Minima/Break-off Height (BOH - remember those???) could not commence until the aircraft was within +/- 15º of FAT. Once the aircraft reported at Procedure minima/BOH the aircraft had to be maintained within +/- 5º of the FAT, which could be tricky the closer you got in, if one hadn’t ‘sussed’ the wind.

I well remember the workload as a Stude at Shawbury when working one aircraft in the ‘DF Simulator’ phase! A tour at RAF Leeming when it was a real flying unit soon cured that; doing 4 QGHs at a time because the AR-1 was off the air (again!) soon got the CADF tube ‘talking’ to you. I even devised a ‘Triangular’ pattern QGH for RW 34 (based on the Shawbury RW 01 QGH procedure) that worked fine (even allowing for Dishforth’s Circuit) as a ‘DF to PAR’ to cater for when the AR-1 was off.

Job satisfaction: off the scale!

The Safety Lanes were the +/- 60º, +/- 15º & +/-5º sectors referred to above. Never, ever, heard the term Safety Path in all my 25+ yrs.

[KN647]

Thank you.
I think that explanation about wraps it up, sorry about the Safety Lane & Safety Path deviation, must be old age. Being lead up the Garden Path . . . . .

Once again THANK YOU ALL for your explanations.

Regards, NICK