Danger of letting down based on NDB false overhead. B707 crash 1974
 

https://web.archive.org/web/20000305...s/740422-0.htm

An accident report worth re-visiting. In 1974 a PANAM Boeing 707 was en-route Hong Kong to Bali at night. There was no DME or ATC radar at Bali in those days. The crew of the 707 planned on an NDB instrument approach on arrival. Forecast was fine but it was a black moonless night for arrival.
Approximately 30 miles north of Bali one of the two ADF's on the 707 swung and the crew misinterpreted this as an indication that the aircraft was overhead the real Bali NDB. They commenced the instrument approach as per the NDB chart. The aircraft crashed into a mountain.

Today blessed with highly accurate GPS position fixing this type of accident would be unlikely. But there are airports around SE Asia and in Australia still with an NDB as the let down aid. The PANAM 707 crash 43 years ago should remind pilots that ADF false overheads can still remain a trap to an unwary crew.

Well, with the GPS usually comes the ability to fly RNAV, RNP, GPS approaches etc!

I can't even select or tune NDBs on my Maxibus; can only see them on the ND via the NDB button on the EFIS control panel.

Even GA operators seem to have all the bells and whistles these days! But yes. Nice to have a reminder that there are traps out there for the unwary in all aspects of flying!

Centaurus,

Interesting. Do we know whether both ADFs were tuned to the same NDB. I do not know Bali and I do not know what other aids would have been available or needed. For example, did the procedure require another NDB to be tuned as well? If both ADFs were tuned to the same NDB, I would have been very wary of only one needle swinging round.

Also, do you know more about the weather at the time? Although the sky was reported to be clear with the stars bright and the sky moonless, presumably that was at the airfield. Were there any active Cbs close to where the needle swung and they turned onto the new heading? I have certainly seen ADF needles point to a Cb instead of the NDB.

What's an NDB approach?:}

NDB = Never Done Before! :ok:

I was 12 years old and in an Ansett 767 cockpit when the captain explained to me the dangers of NDB's after I queried the needle oscillations. I never forget it since.

My AD still has an NDB and I get tested every year but I also recall on two occasions in past decade getting caught out
One failing to monitor NDB on last segment and have the old KR86 switches go noisy and giving false bearing. Saw the Grampians on RHS of the aircraft and had decided not to descend to 20 mile lsalt early like some people do was not on track and would have hit Mt William like a guy called Wills did decades back.
Second was at Temora flying by a thunderstorm needle pointing to cloud did not see station passage let down in valley approaching YOUNG between ranges.
Still alive and still doing NDB approaches and will stack them against NPA GNSS any day.
Tricks with NPAs are to do them correctly and how they send you 15 miles away from the airport whereas NDB is done from overhead and you often get cloud breaks and can get visual. FWIW 2 cents.

Friend of mine saw this thread and wrote thus:

"Back in the days before they had radar at Bali, I was ferrying an F 27 from Muscat to Christchurch. On board I had a trainee Captain and a low time First Officer. Most of the sectors were conducted with me supervising from the jump seat when the Captain was flying and from the left when giving the F/O a leg.

Inbound to Bali, at night, I was having a bit of a snooze down the back, with the intent to go forward for the approach, as none of us had been to Bali before. I heard the engines throttle back for the descent and thought to myself “hmmm...a bit early, maybe we had good tailwinds?” Went forward to note that they had set 4000 feet on the alt alert. “What’s happening?” Says I. “Cleared to the NDB, 4000” says they. So, of course I stopped further descent while looking up the MSA, which I knew to be high to the north. Lucky I did. Seems that back then, if there was no conflicting traffic ATC cleared aircraft down to the IAF or FAF without any regard to terrain. It was assumed that the crew would fly the necessary procedure – which in this case involved ‘shuttling’ down in the holding pattern.

Lucky I have a built-in time and motion meter, hey? "

I tucked a point away years ago at Hobart.

On the 727, flying with some chap I had never met before. CAVOK, night, and cleared for the usual .. but he decided to stay at LSA plus until overhead the aid and fly the full letdown using other aids to confirm position as available. Perhaps a bit overly cautious but, in post flight discussion, he observed that it was his way to get to retirement when faced by aerodromes into which he had never operated before.

I gave it some thought over an ale and figured that it might not be too bad a tactic for new places ?

John,

I agree one hundred percent!

Post No.8 got me thinking about premonitions. In this case the resting F27 captain who on hearing the engines throttled back for the descent into Bali thought to himself "hmm..a bit early maybe we had a good tailwind." And thus saved a certain CFIT.

It reminded me of a similar feeling or premonition that happened to the captain (Centaurus) of an RAAF Avro Lincoln four engine bomber during a long distance flight from Darwin to Townsville via Cape York peninsula on 9 December 1959. The Lincoln departed Darwin at night and was scheduled to at Townsville about 0600 next day. Flight time was nine hours of which 30 minutes was day. There was a crew of nine aboard including two pilots and a navigator.

Some time after the aircraft turned the corner at Cape York for the southbound track off the coast towards Townsville, the captain gave control to the co-pilot and put him in the captain's seat and slipped down the back for a quick kip behind the main spar. He asked the navigator whose position was in a compartment immediately behind the pilot station, to keep an eye on the new co-pilot and to wake the captain when 30 minutes out of Townsville. Cruise altitude was 1500 feet over water. After all the crew were supposed to log all shipping they may see on the way

Some indeterminate time later the captain woke up with a start and quickly made his way back to the cockpit only to discover the navigator slumped asleep over his charts. Worse still, the co-pilot was also sound asleep and the aircraft was on autopilot.

In the Lincoln the co-pilot seat was a fold down type and when not in use was secured against the fuselage wall. This allowed crew members to walk or crawl into the nose compartment. On arrival at the cockpit the captain saw the altimeter showing 1500 ft and that the aircraft was in low cloud. There was no time to wake the co-pilot and get him out of the captain's seat. Although standing up in the aisle-way he disengaged the autopilot and applying full throttle to all engines pulled back the control column.

Within seconds the aircraft came out of cloud into clear air at 2000ft with dawn coming up on the left horizon. Dead ahead at 12 miles with only the summit poking clear of cloud, was Mount Bentley at 1798 feet elevation the highest peak of Palm island. If the captain had not woken sensing something was not quite right the aircraft would have flown into the hill within a couple of minutes.

Bergerie1. Sorry but can't help you on that lot. Apart from the published official Indonesian investigation, unable to locate more pertinent info. Presumably there would have been a US NTSB investigation but could not find it on the internet.

Centaurus,

Thanks for looking. The premonition you describe sounds just like those described by John Farley!

Have seen TS cells give station passage before.

With respect to the PanAm accident could terrain shielding be a possibility for a false station passage if the aircraft was at the LSALT while still well to the north?

Can I add another question re PA812: What about the INS? The accident report makes no mention of it.

Speaking (or writing) of getting to retirement, when I worked at Bankstown, I was asked to accompany a young, inexperienced bloke on a bank run. He'd been flying with another bloke on this run, but not yet experienced enough to do it on his own. The usual pilot was unavailable (ill, or something. I forget why). I didn't work for this company so wasn't familiar with the route or routine. This was pre-GPS.

We did the trip. There were some issues but the worst was the last sector. Young bloke in the LH seat, me supervising. Returning to YSBK at night in IMC over the Blue Mountains to the west. En-route, and without any fix whatsoever - not even a groundspeed check - he decided it was time to start descent into YSBK, using the LSALT step downs.

I had to stop him. He said that's what the other pilot did. The problem, in my mind, was that hadn't confirmed - or determined - he had passed the mountains! Not even a groundspeed calculation. Everything based on flight plan times.

Debriefing afterwards, I had to emphasize that were there headwinds stronger than forecast, or a TAS less than planned, we would have descended into the mountains - but he had no way of knowing that. I said that if he wanted to descend early he needed to pre-determine x-bearings (+ tolerances) from navaids to give fixes to allow that.

In my mind was a historical crash written about in the old ASD ('crash comics'. Nothing so useful in its abysmal replacement!) about a plane that used ded. reckoning for its descent and the winds weren't as expected. End result was a premature interaction with the Great Dividing Range.

ampan, No INS on 707s at that time.

Centaurus, this is all that's available on the NTSB site. Seems access to the file would have been removed in January 2001.

https://ntsb.gov/_layouts/ntsb.aviat...id=83155&key=0

Retrieval would have been tough work, caution, brief glimpse of body.



Although the report doesn't directly say so, it seems to hint that both ADF were tuned.

luckily the industry is slowly grinding forward. if only one step at a time.

whilst there may still be ndb approaches, its been a few years (and several jet types) since i was in an aircraft with an adf installed.

the premonition tales ring true. thanks for posting.

I remember once doing a practice NDB approach in a Chieftain with dual ADF, both tuned correctly to the aid.

One showed station passage at least 10 seconds before the other!:hmm:

`Why is it so?`(In my best JSM accent:D) I queried the C&T Pilot in t`other seat.:confused:

`You`ve just learned something important!` was the reply.

ie; Cross check with DME (then) or GPS. (now):=