High Altitude Approaches

germb747

Well-Known Member
The definitive answer would be the controller but this chart for Nellis specially states NOT FOR CIVIL USE.

Hadn't done one of these for decades and a bit surprised they begin at such a low altitude. Ours (decades ago) usually started at 20,000ft instead of the 10-11,000ft on these charts.

http://204.108.4.16/d-tpp/0808/00227HT3R.PDF
Yea, clearly the approach you posted isn't for civil use, probably because it's TACAN based (and how many civilian planes are TACAN-equipped?). The one I posted for San Angelo uses VOR/DME "or" TACAN and doesn't say "Not For Civil Use", so I don't see any reason why a civilian couldn't fly it. Not that I had ever heard of these kinds of approaches before joining the mililtary, so I guess probably most civilians don't know about them either.

BTW, Midland used to have a really cool high penetration to the ILS RWY 10, but I can't find it; hopefully it wasn't discontinued because that was a fun one.
 

Stomp16

You mean Shennanigans?!?!
I know nothing of military operations but, this tweaks my interest. Why does the military need approaches of this sort? -4000fpm in a KC135 sounds like a hell of a good time! :nana2:
 

Orange Anchor

New Member
I know nothing of military operations but, this tweaks my interest. Why does the military need approaches of this sort? -4000fpm in a KC135 sounds like a hell of a good time! :nana2:
They were called 'high altitude penetrations' when I was flying them. You would come in and stay high until you wanted to come down and land. I guess the idea was to stay above small arms fire, etc in hostile areas and then come down quickly before the bad guys had a chance at you. I would say it was also for fuel savings but we flew the patterns then with the gear down and flaps 30 so we didn't wear out the systems (I'm not making this stuff up). Needless to say, we burned a LOT of fuel and a rough rule of thumb was 10% of your gross per hour so at 160,000lbs, we vaporized about 16,000lbs per hour.

My Ops officer took approaches and turned them into math problems and when he flew them, it looked like the airplane was programmed. This was more than 30yrs ago so we didn't have the ability to lock the autopilot into an FMS (??? flight directors were NEW)

John was quick at figuring his numbers. For example, he would use his mach number (for example 0.60) to calculate his time to travel the distance (about 6 miles per minute). Distance divided by time would give him his required VSI. And if for instance, he needed 4000fpm, he would multiply his mach (mach number times 100 equals VSI with each degree of pitch.. ie, 0.60 mach for each degree of pitch change the VSI is 600fpm). 4000fpm in this case requires the nose to lower about 6 or 7 degrees.

It takes longer to type this stuff out than it did for John to run his numbers. He would ask the nav for drift before his turn and either add it or subtract it from the bank angle for a standard rate turn and again, like I said, it all looked like it was an FMS approach before we had FMS approaches.

Add to the fact the tanker can come down like a rock. It was not unusual to drop the gear, pull the boards up to a full 60deg and at idle thrust, peg the VSI at 6000fpm. In emergency descents, we did the math and it was not unusual to have descent rates at around 10,000fpm.

None of the stuff I later flew (737, 757, 767, Airbus) had the drag capabilities of the old tanker. It is going to be hard to replace.
 

germb747

Well-Known Member
Yes, they're still called "penetrations" (maybe this thread would get more attention if I titled it that :D), and yes they're fun as hell!

I looked through 11-217 Vol. 1 and Vol. 2 to see if they laid out a rationale for these approaches, but I couldn't find one. I believe part of it is for the tactical benefits already mentioned, but they may have also been built to take place of an 'enroute descent' in certain non-radar environments and/or places with inhospitable terrain where we don't trust ATC. Such an approach can be easily built in theater to get aircraft safely out of the enroute structure to transition to an IAP.

We sometimes fly them in the heavy world, usually just for fun as we're not required to log them off as training events, but perhaps a fighter pilot could shed more light on them--they appear to use high penetrations way more than we do.
 

Orange Anchor

New Member
We did some fairly goofy stuff under the guise of 'tactical'. One was to come into the airfield at around 200kts and 1000ft. When the runway went under the nose, power to idle, gear down, flaps 50 and speedbrakes to max. Drop the nose about 8deg below the horizon.

At 200ft, you stowed the speedbrakes and began pulling the nose up. All this in a -135! They class 26ed a tanker doing this and decided that the training and lack of actual demonstrated need combined to remove this from the training syllabus.

I never did one but rode through a few and it always seemed like a great way to tear up an airplane if not kill yourself. One of the guys in our squadron, Leo, was the one who crumped the airplane.

And too, the high alt penetration will save fuel over an enroute descent IF you don't have the throttles to idle during the enroute descent. And they are, like the overhead pitch, a quick way to get a lot of airplanes on the ground.

On my inst check in the -38, I was flying with one of the wing weenies and we were doing a penetration. After we started down, he said or mumbled, "I've got it" and I never heard him tell me I had it. He was known for riding the stick. So here we are plummeting toward the dusty west Texas dirt and he said, "We sure are coming down!" and I think that is an accurate comment but after all, he is flying it. He says something again like, "Isn't this a bit steep?" and both of us realize no one is flying the White Rocket. NOT GOOD!

When I was in the 737 training dept, everyone knows the 737 will not come down very well IF you just use boards. So a friend of mine and I had an open sim and we went in for some fun. We put the sim at FL350 and about 250kts indicated. Although the Boeing says 20,000ft is the max alt to extend the gear, we dropped the gear, pulled the throttles to idle, pull up the boards and went up to max gear speed of 320kts. We stayed at 320kts until 3000ft AGL and from 30 miles out, we would be able to not only land but have to spool up on final. Had we not seen it, neither of us would have believed it. Nice to know information if you are on fire.

I know a lot of guys knock the check airmen and the sim guys but if you really want to learn an airplane, go into training and try to teach it. And yes, the sim is not the airplane but more and more the sim fidelity is getting closer and closer to the airplane. I really enjoyed my time in training... and learned a lot about airplanes and people.
 

germb747

Well-Known Member
You can get about 1000 ft/nm out of a fully configured C-5. Alternatively, I don't recall what the descent gradient is with 350 KCAS and thrust reversers but you come down fast!
 

Orange Anchor

New Member
You can get about 1000 ft/nm out of a fully configured C-5. Alternatively, I don't recall what the descent gradient is with 350 KCAS and thrust reversers but you come down fast!
Concorde had no speedbrakes but you could reverse the inboards like on a DC-8. The story was Speedbird was coming into NY and ATC was late in giving them a descent. Oddly enough, like big recips, you couldn't just pull the engines to idle on Concorde but had to reduce power gradually. ATC told Speedbird to cross ABC fix and Speedbird advised they were unable. The controller told them, "You can use reverse on your inboards, can't you." The Capt replied, "I can but they are for me to correct my mistakes.. not yours."
 
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