nap of the earth, how low is low?
Thread Starter
Join Date: Jul 2003
Location: Port Townsend,WA. USA
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
nap of the earth, how low is low?
I was a passenger in a Jetranger flying about 5 feet agl over the treeless tundra in Alaska. We were also headed up a slope of about 10 degrees, for a mile or so. How difficult was this for the pilot to fly this low and was it extremely stupid?
What is the normal minimum height for terrain or nap of the earth flight?
Thanks
slowrotor
What is the normal minimum height for terrain or nap of the earth flight?
Thanks
slowrotor
Join Date: Apr 2003
Location: USA
Age: 75
Posts: 3,012
Likes: 0
Received 0 Likes
on
0 Posts
Ouch! If the terrain has small and large features, like grass and brush, the job is fairly easy, but requires flawless attention to the task. A foolish and hazardous thing with passengers, IMHO. At 50 to 100 feet, it would be very impressive and much less hazardous. At 500 feet, it would be cake, and even allowed by law.
True NOE is tactical, and saves lives in combat, when bad guys want to shoot you. Otherwise, we don't call it NOE, we call it foolishness, and the guys who issue licenses call it illegal.
True NOE is tactical, and saves lives in combat, when bad guys want to shoot you. Otherwise, we don't call it NOE, we call it foolishness, and the guys who issue licenses call it illegal.
Join Date: Jun 2006
Location: NT, Australia
Age: 42
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
5' agl + high speed + single engine = dissaster. Even in a twin you would only fly like that if abosolutley necessary.
I am sure all of us have gone low from time to time for a thrill but not with passengers.
I am sure all of us have gone low from time to time for a thrill but not with passengers.
Back in the time of Dinosaurs, Ol' Nick and I went through the US Army Aviation School where they told us we were helicopter pilots. At that time we all learned everything about the "Dead Man's Curve" commonly known to civilian pilots as the Height Velocity Curve or H/V to Bell drivers. We were well versed in flying "Low Level" or by means of a method called "Contour Flying". Both methods were designed to allow us to avoid the dreaded "Dead Man curve" even if it prevented us from being able to get to a safe forced landing area if we had an engine failure. (think single engine aircraft here).
While we were away on our Senior Trip....we were told to forget about Low Level and Contour flying and start flying at heights of 1500' or more and to avoid being repetitious and committing sins like following terrain features and roads and such.
After that period of unpleasantness between our employer and some Southeast Asian gentlemen, our employers took on some old business with folks who liked Bears. It seemed the Bear Boys had lots of tanks, mobile anti-aircraft guns and the like and seemed very willing and capable of using them.
Our employer realizing the old SEA method of flying at specified heights above the ground for administrative and seperation of aircraft types would not work well in the now rather hostile threat enviroment.
We then were told to fly "Nap of the Earth" known by the working class as NOE. There we learned to vary our airspeed, speed across the ground and height from obstacles and such as required to remain out of sight like our bosses did whenever there was work to be done. Amazingly enough....there was no more mention of the H/V curve or Dead Man's Curve lest one be flogged for Heresy and Back Sliding.
Thus....assuming what Ol' Nick and I were taught there is either no safe height to fly or no unsafe height to fly....but one thing is certain....bend your birdie and you will be wrong.
While we were away on our Senior Trip....we were told to forget about Low Level and Contour flying and start flying at heights of 1500' or more and to avoid being repetitious and committing sins like following terrain features and roads and such.
After that period of unpleasantness between our employer and some Southeast Asian gentlemen, our employers took on some old business with folks who liked Bears. It seemed the Bear Boys had lots of tanks, mobile anti-aircraft guns and the like and seemed very willing and capable of using them.
Our employer realizing the old SEA method of flying at specified heights above the ground for administrative and seperation of aircraft types would not work well in the now rather hostile threat enviroment.
We then were told to fly "Nap of the Earth" known by the working class as NOE. There we learned to vary our airspeed, speed across the ground and height from obstacles and such as required to remain out of sight like our bosses did whenever there was work to be done. Amazingly enough....there was no more mention of the H/V curve or Dead Man's Curve lest one be flogged for Heresy and Back Sliding.
Thus....assuming what Ol' Nick and I were taught there is either no safe height to fly or no unsafe height to fly....but one thing is certain....bend your birdie and you will be wrong.
Join Date: Jul 2000
Location: London
Posts: 2,916
Likes: 0
Received 0 Likes
on
0 Posts
I assume you gave 500 feet as an example safe height, not as a legal minimum, and meant illegal under FAR 91.13 'Careless or reckless operation' which doesn't specify any minimum height but does cover endangering people in the aircraft.
Helicopters flying across the Alaskan tundra would (I assume) be legally allowed to fly lower than the 500 feet minimum height specified in FAR 91.119(c) by virtue of the exemption in 91.119(d) - provided they comply with the conditions of the exemption.
(We don't have that very sensible exemption in Europe.)
Tudor
I thought that that was (effectively) the UK ruling...My (very limited) understanding of the FAA ruling was:
Sec. 91.119 - Minimum safe altitudes: General.
Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:
(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.
(b) Over congested areas. Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.
(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.
BUT:
(d) Helicopters. Helicopters may be operated at less than the minimums prescribed in paragraph (b) or (c) of this section if the operation is conducted without hazard to persons or property on the surface. In addition, each person operating a helicopter shall comply with any routes or altitudes specifically prescribed for helicopters by the Administrator.
So, in this Alaska/B206 scenario, he wasn't contravening any FARs but he was just a 'sneeze' away from disaster...
Apologies in advance for the egg-sucking lesson.
Join Date: Jul 2000
Location: London
Posts: 2,916
Likes: 0
Received 0 Likes
on
0 Posts
He wasn't contravening 91.119 but, as Nick said, the flight would be illegal if it endangered any person (in or out of the helicopter) in contravention of FAR 91.13 'Careless or reckless operation, endangering etc.'
Key point folks......
As to the other rule...."Careless and Reckless" ...usually winds up being whatever the FAA cares to call it but in court there must be some sort of violation. An example was the head lopping done by a 412 pilot hauling skydivers in Illinois a few years back.
He chopped off a photographer's head with the main rotor blades of a 412 while on takeoff over a corn field while hauling a full load of sky divers. He was found not to be in violation of any rule, regulation, or law.
For those of you that have never been to Alaska....there are places up there where one could fly all week and never see a person, structure, or vehicle except at your base of operations.
without undue hazard to persons or property on the surface.
He chopped off a photographer's head with the main rotor blades of a 412 while on takeoff over a corn field while hauling a full load of sky divers. He was found not to be in violation of any rule, regulation, or law.
For those of you that have never been to Alaska....there are places up there where one could fly all week and never see a person, structure, or vehicle except at your base of operations.
Thread Starter
Join Date: Jul 2003
Location: Port Townsend,WA. USA
Posts: 440
Likes: 0
Received 0 Likes
on
0 Posts
A few more details...
This was in '74, so memory is cloudy, I was working for an exploration company that had three jetrangers at a base camp in Umiat Alaska. My regular ship was down so my crew flew that day with this "other" pilot when the low flight incident occurred. Glad I never had to fly with him again!
We must have been going near cruise speed (100 to 120mph) would be my guess as we were enroute to the work site. But it may have been something more like 50 or 60, to answer Whirlygig's question.
Sasless is correct, nothing to hit for miles except maybe a bear and they were usually good about getting away (they hate helos), that's another story.
I wasn't thinking of an engine failure in the HV curve, I am well aware of that risk. But rather just how risky it is to fly low over open terrain. What would happen if the skids hit the ground in cruise? Would it rip the skids off?
I have seen airplanes touch wheels on water in cruise, no problem.
This was in '74, so memory is cloudy, I was working for an exploration company that had three jetrangers at a base camp in Umiat Alaska. My regular ship was down so my crew flew that day with this "other" pilot when the low flight incident occurred. Glad I never had to fly with him again!
We must have been going near cruise speed (100 to 120mph) would be my guess as we were enroute to the work site. But it may have been something more like 50 or 60, to answer Whirlygig's question.
Sasless is correct, nothing to hit for miles except maybe a bear and they were usually good about getting away (they hate helos), that's another story.
I wasn't thinking of an engine failure in the HV curve, I am well aware of that risk. But rather just how risky it is to fly low over open terrain. What would happen if the skids hit the ground in cruise? Would it rip the skids off?
I have seen airplanes touch wheels on water in cruise, no problem.
Gatvol
Join Date: Jun 2000
Location: KLAS/TIST/FAJS/KFAI
Posts: 4,195
Likes: 0
Received 0 Likes
on
0 Posts
Nic hit the nail. NOE is for Military and anyting else places lives in danger.
Bet your flight was on a contract with some youngster wearing Ray Bans.
Probably out of FAI.
You cant see anything that low anyway so its nicer to fly higher and enjoy the scenery. Believe it or not a Bear will take a swat at you if you come that close.
Bet your flight was on a contract with some youngster wearing Ray Bans.
Probably out of FAI.
You cant see anything that low anyway so its nicer to fly higher and enjoy the scenery. Believe it or not a Bear will take a swat at you if you come that close.
I am confused ,,,what is the relevence of the avoid curve with relation to NOE flying ? At 120 kn in a 206 you could flare up to 500ft to initiate your landing. I am not saying that particular flight was safe but there is no doubt that you CAN fly safely at 10ft and 100kt over flat ground safely, even in a single.
nigelh,
I suggest that you have another look at your flight manual. (Specifically section 4-17 for the B206).
100kts @ 5ft puts you right in the middle of the 'high speed' section of the H/V curve. ie in the event of an engine failure, you won't have time to react before the aircraft has contacted the ground.
And that obviously doesn't take into account the 'sneeze factor'...
It also says that a 200 ft hovver puts you in the middle but in reality you can quite happily put it down safely from this altitude. Dont confuse the book with FACT. I am not saying it is advisable , just that it does not mean you crash. As for the low level stuff, i know of dozens of engine failures at around 10 ft and not one of them hit the ground as you say , the pilots had time to **** it up a hundred yards later after climbing !!
Join Date: Jul 2000
Location: London
Posts: 2,916
Likes: 0
Received 0 Likes
on
0 Posts
Bravo73
Is it possible there's a difference between what can actually be achieved with an aircraft by experienced pilots and the limitations imposed for safety reasons by certification authorities in conjunction with the manufacturer?
Surely the limitations are pitched at a 'safety level' which will be more conservative than what the test pilots actually achieved in testing?
Is it possible there's a difference between what can actually be achieved with an aircraft by experienced pilots and the limitations imposed for safety reasons by certification authorities in conjunction with the manufacturer?
Surely the limitations are pitched at a 'safety level' which will be more conservative than what the test pilots actually achieved in testing?
Last edited by Flying Lawyer; 19th Jan 2007 at 18:54.
Tried NoE over Lafonia in the Falklands with a pair of F3s chasing me. 200kts GS, noise to 10' on the Rad Alt (with the occaisional sheep setting it off). B******d if I could find any cover.....! Agree totally with the other far more erudite and experienced aviators on this site; true NoE is a balance between threat and flight safety. We stooged around at 50'agl at night during GWII right up to the point when the Cdrs accepted the RF SAM threat had gone away. That tipped the risk equation and we bumped up to 100' day / night for flight safety reasons. The ground has a PH of one and a PK of nearly one, honour the highest threat.
As for infringing Licences & civil laws, well I suppose rule 1 applies. Just don't endanger anybody else with your shenanigans!
NoE at trg weights in a powerful helo, ie CH47, isn't particularly dangerous in terms of pwr loss when you can hover OEI OGE! It is also important to stress that the majority of true NoE military flying is conducted at a fast hover taxy during advance to fire posns and Concealed Approaches & Departures (CADs).
Can't deny that it's fun though!
As for infringing Licences & civil laws, well I suppose rule 1 applies. Just don't endanger anybody else with your shenanigans!
NoE at trg weights in a powerful helo, ie CH47, isn't particularly dangerous in terms of pwr loss when you can hover OEI OGE! It is also important to stress that the majority of true NoE military flying is conducted at a fast hover taxy during advance to fire posns and Concealed Approaches & Departures (CADs).
Can't deny that it's fun though!