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Flying to Mt Hotham in a 172
Has anyone flown a 172 ( 160 HP) into Hotham ( 4460 ft AMSL) . The POH numbers tell me it shouldn't be a problem,..but have never done it before.
The Hotham pilot guide advises a 4.8% climb gradient is needed to clear the ridge off RW29. This works out to be about 350 ft / min climb at 70kts. I plan to lean to max RPM at full power on Take Off. We will be well under max wt, with 2 POB ( 900 kg vs 1043 MTOW) . Everything tells me it will be fine...but. still a little nervous. Any tips from the pros? Its an older N model aircraft so would not be surprised if performance is a little under the book values. Also interested in any advice on the route ( in and out ) to take from Melbourne area. Cheers Terry |
C172 performance
There are also many other factors to consider such as mountain waves etc. Are you familiar with the machines performance? Not all same models performe the same or anywhere near book figures. Why don't you load it up to the same weight and take it to the same altitudes and see what sort of clumb rate you get. I was once in the mountains with a lightly loaded early model C210, and we were just holding altitude. Try and get yourself the Kiwis handbook on mountain flying, well worth a read.
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And importantly from ERSA "PPR FM AD OPR for all non RPT before OPR into AD."
Call them and talk to the people on the ground who really know. They should have reliable answers to most of your questions, and they're likely to be justifiably upset if people just turn-up without permission. |
The Mount Hotham ARO is a good guy. Call him. The issues with Hotham are more weather related than altitude related. Its subject to fog, haze and local cloud all of which can change rapidly. Unless the day is 8/8 blue, don't be committed to getting in or out at a particular time. The snow cams can be useful, but the weather can vary significantly from the summit to the airport.
The runway has quite a bit of slope which creates a bit of a challenging visual reference on final approach. Its easy to get too low. If you struggle for climb on take-off you can turn to the right toward lower ground. Especially for your first time, it would be better not to be heavily loaded. |
An appreciation of slope lift is also good insurance in any high & hilly country - e.g. getting Crowley's 172 ARK out of the highlands with a load on and a hot day..... Know the wind direction & shape of the ridges.
Same point applies to downdrafts, if you just clear a ridge with the wind behind you. Lots of traps in the high country. |
Remember yr 160 HP is severely hamstrung at that Alt & a FP prop, the HP won't be there. Rated HP at take off is NEVER what the engine is capable of with a FP prop & normally aspirated.
Id pick yr day to do this, early morning, light winds & always have an 'out' I've been in there once & the terrain is magical but is a hazard! |
As a last resort ( if you are still not sure of climb performance ) when you fly in conduct a go around from say 500’ above airport elevation with an escape route in mind and see how she performs at 70 knots......if it doesn’t go very well and you are not confident divert home and don’t land? as Cessna200 says above you could do this before leaving your local area. Setup for takeoff config at 5,000’ and fly level at about 60 knots, then apply full power and see how it accelerates and climbs at 70 knots.......should give you a good idea show she performs at 5,000’ Very sensible question you ask and I’m sure you’ll be fine after some research. |
Not saying I am an expert of any kind here but I know that with most older cessna types the book figures are rather generous to say the least. As a rule for field performance I typically add another 20% to the figures, as for climb I use a simple rule of thumb that I have tested over the years in various types at various altitudes. I always consult the POH first and then I use this formula that gives me figures slightly less than the best climb for max weight. As alt increases the rate reduces and after about 4-5000ft on a standard day it deteriorates quite rapidly, these are somewhat lower than the book figures and further below the higher you go but I find it easy to use while in flight. goes like this:
(Rule of thumb only based on max weight, so hopefully anything less should have marginal improvement) Climb Rate C172 1000ft is roughly 650fpm averaged out, after that I use this formula: Loose 50ft per 1000ft starting at 550fpm @ 2000ft 2000 = 550fpm 3000 = 500fpm 4000 = 450fpm 5000 = 400fpm 6000 = 350fpm 7000 = 300fpm 8000 = 250fpm 9000 = 200fpm 10 000 = 150fpm This I have seen for the "N" and "R" models in particular with a 160Hp engine and old prop, one frame had something like 6500hrs on it and clearly a bit tired where it only "just" did better than the figures I have above, this was on a cool day with dense air and I am certainly no test pilot! Not being that familiar with mountain flying I am also looking in to doing Hotham one day but will perhaps jump in with an instructor who has some experience and also in something with a few more nags up front like a 182T and a light load. I have heard a few horror stories of weather around that part of the country and again I'd only do this flight on an almost perfect day. Good luck and would really like to hear how your trip goes. :) |
What is going on here? This is PPRuNe not one negative post! p.s. I only weigh 109kg can I sit on the back seats? Have a great flight mate, awesome the prune community steps up. Doez Hotham have the airport webcam? Only ever flown in there once but had kero burning and it was in a different century! |
Originally Posted by Cessna 200
(Post 10477570)
Try and get yourself the Kiwis handbook on mountain flying, well worth a read.
If you are blocked pm me and I'll send you a copy via other means. |
Originally Posted by Global Aviator
(Post 10477954)
What is going on here? This is PPRuNe not one negative post! p.s. I only weigh 109kg can I sit on the back seats? Have a great flight mate, awesome the prune community steps up. Doez Hotham have the airport webcam? Only ever flown in there once but had kero burning and it was in a different century! |
Originally Posted by flyinkiwi
(Post 10478224)
Free download from the NZ CAA website.
If you are blocked pm me and I'll send you a copy via other means. |
The NZ crowd sure do it properly ! Their info on spinning is invaluable also!
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Both books downloaded! Gold! |
The NZ crowd sure do it properly ! Their info on spinning is invaluable also! I will also give a vote for the ARO at YHOT, he is a switched on guy and super helpful and friendly. |
Originally Posted by Sunfish
(Post 10478263)
Both books downloaded! Gold! |
Originally Posted by Squawk7700
(Post 10478252)
No webcam up there and not likely to be unfortunately. I’ve been advised by management that it won’t be happening. |
Originally Posted by Squawk7700
(Post 10478252)
No webcam up there and not likely to be unfortunately. I’ve been advised by management that it won’t be happening. Plus, an accessible & helpful ARO on mobile. |
Originally Posted by machtuk
(Post 10477628)
Remember yr 160 HP is severely hamstrung at that Alt & a FP prop, the HP won't be there. Rated HP at take off is NEVER what the engine is capable of with a FP prop & normally aspirated.
Id pick yr day to do this, early morning, light winds & always have an 'out' I've been in there once & the terrain is magical but is a hazard! If if you are worried, just go out tomorrow and climb to 5000 ft and see what climb you get. Remember to use redline, not some lower limit imposed by a flying school to protect its engines. Hotham has effectively 1500m of runway. Heaps for a C172. If if you turn right on takeoff from runway 29 there is the valley to Anglers Rest. The terrain continues to rise on the left and the terrain is not as clear. if you take off on runway 11 it’s downhill and should be easy. I’d be more concerned about weather than altitude performance. |
Originally Posted by Old Akro
(Post 10479083)
you’ll lose HP due height, but gain it due to low temperature. In Australia you’d be surprised at the density altitude of some of out airports in Summer. 5,000 ft is kids stuff in America where most of these fly. What’s its service ceiling ? 14,000 ft? If if you are worried, just go out tomorrow and climb to 5000 ft and see what climb you get. Remember to use redline, not some lower limit imposed by a flying school to protect its engines. Hotham has effectively 1500m of runway. Heaps for a C172. If if you turn right on takeoff from runway 29 there is the valley to Anglers Rest. The terrain continues to rise on the left and the terrain is not as clear. if you take off on runway 11 it’s downhill and should be easy. I’d be more concerned about weather than altitude performance. |
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