BABS Beam Approach Beacon System

[PaulFrank]

How low, realistically could, or would, BABS approaches be flown to?

Or put in modern terms what was the system minima?

[Pom Pax]

300ft, 1 mile.
No altitude information but distance seemed pretty accurate down to zero. It was possible for the beam to deflected.

[PaulFrank]

That is pretty impressive. Thanks for the information.

[ian16th]

I serviced it circa 1954 at Lindholme.

As an aside, I learnt to drive on the BABS Van! It was the 1st vehicle I ever drove. A Standard 9 with a 3 speed crash gearbox.

[binbrook]

Pom Pax

When BABS was around did our masters set a minimum vis? My memory is that we just came down to the 300ft DH (should have been a mile out) and if you - or more likely in grotty WX your trusty observer - could see a light or two you kept going.

[Pom Pax]

binbrook I am sure you are 100% correct, I only called out the numbers. I recall on an approach against a low watery winter Sun faithfully doing my commentary against back chat of "Can't see a thing" and repeat until at 1 mile, "There's the Royal Oak, ok nav."
I suspect when first introduced Babs was the best thing since sliced bread and Harris' brave boys often had no option but to continue until they saw something. Even well into the fifties GCA was a luxury not available to every station.

p.s. "Can't see a thing" was truthfully the sanitised version. Obviously visual from the pub to home.

[Fareastdriver]

The TBA, the same as BABS but you had a coffee-grinder frequency changer, was in service at Tern Hill in 1960. You found, or were directed by ATC using CADF, to the overhead cone of silence. Once there you followed the procedure and there was an outer and an inner marker.

The 'beam' was audio and on finals at Ternhill you turned right on the 'A's and left on the 'N's. The mix, a continous note was heard when on the centre line. 300 ft rings a bell and flying dual one would be told to look up just as you passed over the hedge at about 50 feet.

[NutherA2]

The TBA, the same as BABS but you had a coffee-grinder frequency changer, was in service at Tern Hill

We had it at Feltwell, too. My last Provost flight (03 Aug 55) shows as 55 minutes solo including 40 minutes IF, this consisted entirely of "beam approaches".

[chevvron]

Is this the same as 'SBA'? Or is the difference that BABS was equipped with 'fan markers' to give dft info?

[Fareastdriver]

TBA/SBA both had fan markers. The reason for the 'fan' was so that somebody who was struggling to sort out the drift to stay on the centre line had a fighting chance of hearing it went he went past. IIRC passing the inner marker without a steady noise was a mandatory overshoot.

I saw the poor old BABS van at Aldergrove being crushed by a Halifax in about 1949. The van fought back by removing the port oleo resulting in the Halifax sliding along the runway sans mainwheel and attachments. As the Halifaxes were approaching the end of their service life it was then a one way trip to the dump.

Halifax 1 BABS Van 1

[oxenos]

"When BABS was around did our masters set a minimum vis? "

As I recall, the R.A.F. did not require a minimum vis until the mid 70's.

[binbrook]

BABS gave range as well as left/right indications and I don't recall any markers. QGH down to 1500ft and at 5 miles start downhill at what you hoped would give 300ft/mile, observer on the 'Rumble' seat and plotter calling 'Dots 1, Steady, Dashes 1, Steady' you hoped, plus ranges - effectively an in-house ACR7. The required landing rate for the stream was one every 3 minutes, and since take-offs had been at 1 min or even occasionally 30 sec apart, with 3 x 16 U/E squadrons on exercises there was sometimes a lot of time to lose in the 'Trombone' on return. Primitive though the system was, it did work.

[Pom Pax]

From a tube watchers point of view, you homed in on the reciprocal bearing of the active runway using Eureka to be overhead at 1500ft. When overhead you switched to the babs freqency'. (Did the tower then give you a heading?) You then called turn 60 degrees right maintain 1500ft calling ranges at 2 mile intervals, at 8 miles the call was "8 miles turn left left". The pilot commenced a level rate 1 left turn and you called the range at 1 mile intervals. This turn should put you on the runway centre line at 5 miles.

Now Babs was what was in the little Standard van and you are interpretating its signals on a Rebbeca set (aurally for solo pilots) visually from a small crt. As the rebbeca was for both eureka and babs, the crt had scales of 12 miles, 60 and 120. We were taught to call either right or left left (and steady?). (I think slightly crept in if we did not want a large correction).

At 5 miles began the continuous patter to balance the two arms displayed on the crt with distance calls and mandatory calls with height checks on the level miles. After calling "1 mile 300 ft" we were supposed to shut up!