Initial cruising altitudes....

[mark]

I was wondering, is there a common altitude that most (if not all) the prop liners climbed to after take off? In an attempt to generate IFR flight plans, I need to enter a cruising altitude so the ATC can let me take off under IFR conditions. During the flight I can request increases in altitude as fuel is burned off.   I was thinking in terms of 16,000', (or 15,000' for those easterly flights), to begin step-climbing.    Any advice would be appreciated. Thanks in advance.

Mark.

[Tom/CalClassic]

Unless you are doing short flights or very long polar flights, 15-17,000 ft is usually fine. You can climb as you burn off fuel.

If you are using a plane with my CalClassic Notepads, there is an altitude calculator for short flights built into the Fuel Planner. Just enter the distance and your IAP altitude (usually about 2,000 ft above the airport altitude) and read the initial altitude. For longer flights, you can set up your weight and distance in the planner, then go to the FE Notepad and get an estimate there.

[mark]

ahhh, many thanks, Tom....I've been plowing about in a DC-3 for too long, very rusty on the pressurized flyers....

[Dennis the menace]

A flight from California to Hawaii for me is usually between 17 and 19 thousand feet. If you can cruise at 17 thousand feet, so much the better, as you can keep your superchargers on low speed. In real life this is better for both the superchargers and the engines. On a transpolar flight with a fully loaded DC-6B or DC-7C it will be rare to get above 15 thousand feet for the first several thousand flight miles. Only near the last 1/3 of the flight can you be light enough to climb to 21 or 22 thousand feet.

Propliners have a sweet spot between 14 thousand and 19 thousand feet. They run best, and are most efficient at those altitudes. Climbing over that, especially if you are heavy, results in a nose up altitude and that leads to drag which slows you down and increases your fuel burn.

I recently flew a DC-7C from Los Angeles to London. I had with enough fuel to make the almost mandatory stop at Frobisher Bay, and then loaded up with the maximum number of passengers and freight that I could carry. I departed the International satellite at LAX with 400 pounds over weight. I taxied to runway 25 left because it was the longest runway at LAX. Takeoff was around 9000 feet, or a little more. You will not climb more than 300 to 400 feet a minute. This is normal for this circumstance. The ONLY way for a trans-polar flight in a Starliner or DC-7C out of LAX is head west after takeoff, make a turn to the south around Palos Verdes peninsula, head towards the Seal Beach VOR. This gives you room to slowly climb over the ocean and takes you out of the way of incoming traffic to LAX. From the Seal Beach VOR you head to Riverside VOR and from there direct towards the Palm Springs VOR. Even though this is east and south, the opposite of how your route should take you, you MUST choose this route because of you slow climb ability, and the proximity of the mountains to the north and east of Los Angeles. From Riverside VOR to Palm Springs VOR it takes you through the Banning pass. The mountains, which are 7 to 9 thousand feet will be on either side of you as you fly through the pass. Once you are at the Palm Springs VOR you are in the open desert, and from this point you can turn north and east. You should be around 9 thousand feet by the time you reach Palm Springs (about 120 miles from Los Angeles - see how SLOW you climb?). From Palm Springs you head towards the Las Vegas VOR, then to Rock Springs VOR, and from there, you fly up to either Frobisher, or Gander, or wherever you are going to stop at. The reason you fly to Rock Springs is because there is another pass through the Rockies. You will only be no more than 15,000 feet until you reach the Hudson Bay, so you will need this pass to get through the Rockies. If you are flying SAS you will do this same departure but at Rock Springs you will fly up towards Winnipeg.

I know this is true because Tom's TWA book describes this route in detail regarding trans polar Starliner flights.

Shorter flights have lower altitudes. Typical 400 mile flight from Phoenix to San Diego won't have you up past 14thousand feet. A flight from LAX to ORD will have you up as high as 21,000 feet, because your not as heavy as a DC-7C. The 1956 TWA United collision had the TWA 1049 Super G flying at 19,000 from LAX to Kansas City. The UAL DC-7 from LAX to Midway was to fly at 21,000 feet. Some stratos across the Atlantic or to/from Hawaii never got above 16,000 feet for the entire part of the trip. So it all depends.

I flight I am doing this very moment has been like this:
Western #209, DC-6B, 70% loaded, KPHX to KSAN, 16,000 feet.
PSA (Pacific Southwest) #603, DC-6B, 90% loaded, KSAN to KBUR, 9,000 feet.
USOA (United States Overseas Airlines)#105, DC-6B, 98% loaded, KBUR to KLAS, 15,000 feet; KLAS to KDAL 17,000 feet; DAL to KMDW 17,000 feet; KMDW to YIP 13,000 feet, KYIP to KLGA 17,000 feet.
LL (Loftleidir)#610 DC-6B 100% loaded, KJFK to BIRK 15,000 increasing to 17,000 feet.
LL (Loftleidir)#618 DC-6B 100% loaded, BIRK to EDDH 15,000 increasing to 17,000 feet.
Pan Am #614 DC-6B 50% loaded, EDDH to EDDI, 7,000 feet. (This is a unique situation, this flight flys through the Hamburg-Berlin air corridor, and is limited to between 3,000 and 9,000 feet in altitude.)

You can see how by 1962 DC-6Bs dominated the low cost economy flights.  I only wanted the absolute cheapest thing that flew!  Total price from Phoenix to West Berlin is $397.25 one way.  Typical coach cost on Pan Am would be $493.15 and first class would be $785.30!

What I wanted to simulate in this flight is how to fly from Phoenix to West Berlin in the cheapest way possible, without having to stay overnight at an airport hotel to make the next days connection. This is it. You leave Phoenix Arizona at 14:20 on a Wednesday and arrive at Berlin-Tempelhof at 23:50 on Friday. There is no need for a hotel. The only gap is arriving at Laguardia at 12:15 on Thursday, and you have to get to JFK for the Loftleidir flight that departs that evening at 19:00. I guess you take a bus, or the subway? Then you twiddle your thumbs until 18:00 when you have to check in for your Loftleidir flight. They did have airport lockers back then, I guess you could check your baggage and then possibly take a city sightseeing tour on a bus? Not sure if they had them at the airport or not.

Hopefully some of these flight levels may help you

[Defender]

Good stuff there thanks Dennis.

Another useful source of flight details is the accident section of the DoT Library here,

dotlibrary.specialcollection.net/Home

In fact the entire library is not a bad way of passing the dark winter days.

At the risk of generalisation, I think it seems reasonable to conclude that when the big props operated the mainstream airline schedules, speed/on-time reputation was the number one priority and hence higher altitudes. Once relegated to secondary routes or charter activity, maintenance/cost became more important, minimising HB use etc.

Examples in the DoT Library:

SAS DC-7C Idlewild direct to Prestwick in 1957. TO weight 138,000 lbs so quite heavy but initial altitude 21,000' which it got to by Nantucket. (Tailwinds might also have been a factor in deciding the best flight level.)

NWA DC-7C McChord to Elmendorf military charter in 1962. TO weight relatively light 125,000 lbs but planned altitude 14,000'. Only when severe icing encountered at that level did the crew request a higher level which showed that the aircraft was quite capable of at least 20,000'. Number 2 engine failed and interestingly maintenance records showed that this climb to 20,000' had been the only time HB had been used in flight during the 202 hours since last overhaul.  

Bill

[Tom/CalClassic]

Yes you have to take into account the wind, because that was usually the deciding factor in altitude selection (after terrain avoidance!).

[Dennis the menace]

I use four main factors to determine cruising altitude:
1. Distance.
2. Terrain.
3. Weight of the aircraft.
4. Winds (I fly with real world weather and have the "download winds aloft" box checked)

1. Distance: Short distances like commuter shorts hops, ie as on Bonanza, Pacific Airlines, Mohawk and Southern rarely got over 9,000 feet. Some didn't have equipment with radar or high speed superchargers. I flew many times on Southern Airways Martin 202s and never climb to more than 6,000 feet or so. Many times we were so low you could actually almost pick out what kind of cars you saw on the highway.  General rule, longer the distance, the higher the altitude that your weight permits.

2. Terrain. Sometimes you cannot climb over mountains so you have to go through passes. This is apparent with transpolar flights out of Los Angeles that need to travel through the Banning Pass to the desert and then turn north. The weight of the payload and fuel prevents these aircraft from traveling due east out of LAX because if you do so, you will only be at 6,000 feet and the mountains are 8,000 feet. Traveling north to say Santa Barbara or San Jose and then turning northeast will get you into a worse situation, as those mountains are 15 to 17 thousand feet high, and your aircraft at that weight will not want to fly correctly over 14 or 15 thousand feet.

3. Weight. If you fly a first class only transpolar, with only 30 or 36 passengers, you can reach 19 or 21 thousand feet within 600 miles of departure. If you fly an all economy flight, with 80 to 114 passengers, you may need 1,500 to 2,000 miles. You can't climb until you burn off fuel and reduce your weight.

4. Winds. While flying a Pan Am transpolar DC-7C flight from KLAX to EGLL with a planned fuel stop at Frobisher Bay, I had flown over 1000 miles northeast from Los Angeles, and was past Salt Lake City, and still my weight kept me at 15,000 feet. I had a tail wind of 13 knots, but according to my wind gauge, up at 17,000 feet the wind had increased to 26 knots. Even though normally my weight would have prevented this move, I climbed to 17,000 feet and was able to increase my ground speed at no additional fuel burn. So in this case, it worked out.

5. Operating economics is something most people never think about when determining what altitude to fly at, but it is of a high importance to airline companies. If you fly to high for your weight, your pitch up will increase. Once you get past .9 degrees pitch up, drag increases, and you must increase the throttle. This in turn increases fuel burn. Companies HATE this. You have to understand airline management. They only think in black or white, no in-between. A flight is either profitable, or it is unprofitable. They do not care about altitudes, scenery, speed or anything else. C. R. Smith was asked once if he bought the Convair 990 because it was considered to be the best looking and fastest jet in the sky.  He answered "I never bought anything because it looked great or how it flew.  I only bought things that I thought could make me money.  My decision to buy the Convair 990 has been the worst business decision of my entire life - hands down." Airlines only want a positive cash flow for each flight.  Running engines at over their normal limits in order to increase your altitude, or speed, or to compensate for drag due to your pitch being too great because your too high for your weight will result in short life and frequent engine rebuilding and associated costs, in addition to higher than normal fuel bills.  This goes into your record, and if it becomes a habit, you get fired.

Over the years, I have seen some people post about how high this or that propliner can fly, and how they flew across the Atlantic at 23,000 or 25,000 or even 28,000 feet. While this may be interesting for scientific methods or for ceiling certification, it is hardly realistic for day to day airline propliner operations. No piston engine airliner had service higher than 23,000 feet. If I recall correctly, I do believe that there was an FAA ban on these high altitudes when carrying passengers due to the lack of oxygen safety equipment. As far as freight flights go, to make the flight as profitable, cargo flights were stuffed as full as could be permitted. If you were just 2 pounds under max weight, then somebody would find a box of candy to stuff in at the last minute. Dollars, and plenty of them are the only thing these airlines want to see or hear about.

Any business exists for just one reason: to make as much money as possible. If they can make money flying passengers and freight, they they will do that. If a business can make more money by selling wine, or shoes, then they will dump the airline and sell wine or shoes. That's how it works - black or white; profit or loss; accounts payable vs. accounts receivable. Business operating economics have as much to do with how to conduct any given flight as does all other variables.

[Tom/CalClassic]

Hi,

The limit for carrying passengers without a complete passenger oxygen system is 25,000 ft. Note that most propliners would not get that high at all, or not until very late in a long flight.

[cj95]

I want to say THANK YOU for this thread!

I have been trying to apply the formulas and tips in the propliner tutorial for determining flight altitudes, but wasn't really sure if I was coming up with the right answers.

For instance, recently taking a ~100 mile hop between Oklahoma city and Tulsa in a Convair 240 I selected 6000 feet as a cruise altitude but in the back of my mind felt kinda guilty like maybe I was cheating or something and should have gone higher.

The math seemed to line up, but I had nothing to compare it to in real life.

Thanks guys for always trying to keep it 'real' as possible.

Any other good references out there?

[Dennis the menace]

It has come to my attention that on Lockheed Constellations, a nose pitch up from +2.5 to +4.5 is considered normal for cruise. I assume this is because the odd fish shaped curved fuselage on the Constellation acts like a wing. I did not know this, since I am a "Douglas" man, myself and do not fly Connies.

There is one exception to these flight altitude guidelines and rules that I know of: and that is the air corridors to and from West Berlin. The only altitudes allowed are from 3,000 feet to 9,000 feet, which is the legal ceiling according to the air rights treaty signed by the allies after the war. This applied even to jets later on and these altitudes must be strictly adhered to or you risk being shot down.

[thomas]

Dennis, please tell us more about this book (of Tom's?) ?

regards
Thomas

Nov 7, 2014 22:40:17 GMT -5 Dennis the menace said:

SNIP

I know this is true because Tom's TWA book describes this route in detail regarding trans polar Starliner flights.

SNIP

[Tom/CalClassic]

Hi,

The book is "Queen of the Skies, the Lockheed Constellation" by Claude G. Luisada. It gives a detailed look at a fictional TWA flight 770, from LAX to London in August 1958. While fictional, it was developed using actual L-1649A performance parameters. This is one route where the Starlner shone over the DC-7C Seven Seas, due to its longer range. The '7C almost always had to stop, usually at Frobisher Bay (in fact, OAG PAA timetables in this era often displayed the location of Frobisher Bay on their route maps, even though they had no scheduled stops there).

BTW, when the original PAA 707-320's took over these flights, the timetable states "fuel stop required". True nonstop flights had to wait for the 320B's. And poor TWA, with only its 707-131's, completely discontinued polar service in 1959 until they got their intercontinental 331's a year or two later.

smile.amazon.com/Queen-Skies-The-Lockheed-Constellation/dp/0764346393/ref=smi_www_rco2_go_smi?_encoding=UTF8&*Version*=1&*entries*=0

[crimar]

Hi:

Dennis, I have made the flight Los-Angeles to Frobisher Bay, in the conditions and the flight plan you explained above, with a DC-7C overloaded with 350lbs pax and fret, after filling the tanks with Tom's notepad for the trip, ActiveSky for the weather (november).
I was at 17500 feet around Hudson Bay, ending the flight at 19000 feet and landind at frobisher with 11% fuel remaining.

Your explanation gave me a serious desire to make your flight!

Thanks to everybody on this forum: I always find answers to my questions here.
Tom: thanks for kindly sharing with your site.

(Hope you understand my english).

All the best.

[lylejf]

Hi:

Dennis and Tom: thank you so much for this information. It turns out my guesses about elevation weren't far off, but it's good to know.

Thanks again, take care.

[thomas]

Hi Dennis
What scenery are you using for the area around Banning Pass? I'm using FS9.1 standard scenery for most of the USA and would like to know how realistic it is. Coming in from LAX via the Pacific to cross the Rockies on the route you've described one can clearly see that this is a low-lying area but I was certainly not grazing my wingtips on the mountain face. Is FS9 realistic in this reagard?

regards
Thomas