# Helicopter landing approach question **URL:** \ **Category:** Factual Questions\ **Created:** [December 7, 2015, 2:23pm UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707 "2015-12-07T14:23:15Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![kferr](https://avatars.discourse-cdn.com/v4/letter/k/71e660/32.png) [@kferr](https://boards.straightdope.com/u/kferr)\ **Post date:** [December 7, 2015, 2:23pm UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/1 "2015-12-07T14:23:15Z")
I live under the flight path of a small airport that services business jets (FAB in the UK). Since I can just glance out the window to see them I’ve started using [FlightRadar24](http://www.flightradar24.com/51.23,-0.99/10) to see what is what. I’ve noticed that the jets all use very similar approach paths when landing from east to west no matter where they originated from. This is very busy airspace with Heathrow and Gatwick not far away so a very regulated path makes sense. Today a couple helicopters landed within a half hour of each other and I noticed that they take the same path as the jets. Even though one of them passed directly over the airport it still did the same loop around that the jets do. I assume that once the helicopter was over the airport it could just go into a hover and descend straight down to a landing. What reasons are there for the helicopter landing like a jet instead of like a helicopter? ---
**Author:** ![SpyOne](https://avatars.discourse-cdn.com/v4/letter/s/82dd89/32.png) [@SpyOne](https://boards.straightdope.com/u/SpyOne)\ **Post date:** [December 7, 2015, 4:11pm UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/2 "2015-12-07T16:11:43Z")
I am not a pilot. I am not any kind of expert. I am basically just a fountain of hearsay. While it is possible to hover in a helicopter, it isn’t exactly easy. Wait, that sounded too harsh. Hovering in a helicopter is difficult. Descending without moving laterally is even more difficult. As a general rule, helicopters seem to descend over distance and only use the hover for the last few dozen feet, when possible. So, “it’s easier” would be my guess. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [December 7, 2015, 4:37pm UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/3 "2015-12-07T16:37:16Z")
It also makes it easier to integrate the helicopter traffic into the fixed wing traffic. All the pilots know where to expect to see other aircraft, and ATC isn’t trying to coordinate the dancing of two totally different approach patterns. ---
**Author:** ![PaulParkhead](https://avatars.discourse-cdn.com/v4/letter/p/7ea924/32.png) [@PaulParkhead](https://boards.straightdope.com/u/PaulParkhead)\ **Post date:** [December 7, 2015, 4:50pm UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/4 "2015-12-07T16:50:38Z")
There’s information about Farnborough available from the [NATS website](http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&task=blogcategory&id=68&Itemid=117.html). The helicopter approach chart shows how VFR helicopters are supposed to approach and depart, and as far as I can tell the routes shown are preferred for noise abatement reasons. More info about that in the “Aerodrome Textual Information” document, section 2.22. ---
**Author:** ![rsat3acr](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@rsat3acr](https://boards.straightdope.com/u/rsat3acr)\ **Post date:** [December 7, 2015, 5:30pm UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/5 "2015-12-07T17:30:20Z")
I flew Hueys in the Army for five years 1980-85. The approach paths are the same for all aircraft under most circumstances. It uses much less power to land at an angle v. hover. Also depending on the situation the helicopter may not have the power to hover out of ground effect(where the ground pushes the rotor wash and gives additional lift), about fifty feet in my old Hueys. At times helicopters may make the approach as normal traffic but once over the landing threshold(end of the runway) may turn directly to a landing spot. Depends on stuff like how busy the field is. ---
**Author:** ![kferr](https://avatars.discourse-cdn.com/v4/letter/k/71e660/32.png) [@kferr](https://boards.straightdope.com/u/kferr)\ **Post date:** [December 8, 2015, 10:28am UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/6 "2015-12-08T10:28:16Z")
Thanks. The noise abatement reason makes perfect sense. The residents around here have made a hobby out of complaining about aircraft noise which is a bit daft considering that there has been an airfield here for over 100 years. The [first powered flight in Britain](https://en.wikipedia.org/wiki/Farnborough_Airport) was made here in 1908. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [December 8, 2015, 11:24am UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/7 "2015-12-08T11:24:27Z")
Another factor, along with fitting in with the other traffic and meeting noise abatement requirements, is that if a helicopter has an engine failure it can successfully autorotate to a safe landing but in order to do this it must have either altitude or forward speed. There are combinations of speed and altitude where you can not autorotate. So hovering at low altitudes but not just above the ground is not a good thing to do. > **[Helicopter height–velocity diagram](https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram)** > > The FAA states "The height–velocity diagram or H/V curve is a graph charting the safe/unsafe flight profiles relevant to a specific helicopter. As operation outside the safe area of the chart can be fatal in the event of a power or transmission failure it is sometimes referred to as the dead man's curve." The EASA refers to it as the "height/velocity avoid curve". > The H–V curve is a diagram indicating the combinations of height above ground and airspeed that should be avoided due to safety conce... ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [December 8, 2015, 3:35pm UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/8 "2015-12-08T15:35:24Z")
> [@kferr](#): > > I assume that once the helicopter was over the airport it could just go into a hover and descend straight down to a landing. What reasons are there for the helicopter landing like a jet instead of like a helicopter? > [@SpyOne](#): > > Hovering in a helicopter is difficult. Descending without moving laterally is even more difficult. > As a general rule, helicopters seem to descend over distance and only use the hover for the last few dozen feet, when possible. > [@Kevbo](#): > > It also makes it easier to integrate the helicopter traffic into the fixed wing traffic. All the pilots know where to expect to see other aircraft, and ATC isn’t trying to coordinate the dancing of two totally different approach patterns. > [@PaulParkhead](#): > > as far as I can tell the routes shown are preferred for noise abatement reasons. > [@rsat3acr](#): > > At times helicopters may make the approach as normal traffic but once over the landing threshold(end of the runway) may turn directly to a landing spot. Depends on stuff like how busy the field is. > [@Richard\_Pearse](#): > > Another factor, along with fitting in with the other traffic and meeting noise abatement requirements, is that if a helicopter has an engine failure it can successfully autorotate to a safe landing but in order to do this it must have either altitude or forward speed. There are combinations of speed and altitude where you can not autorotate. So hovering at low altitudes but not just above the ground is not a good thing to do. > > [Helicopter height–velocity diagram - Wikipedia](https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velocity_diagram) I’m a bit pressed for time this week, but since I have the rating I can’t resist a helicopter question. Noise abatement is an issue at many airports. When I was in training, I started out at Santa Monica Airport (SMO) and the hangar was on the north side of the field. They don’t like helicopters at SMO, and helicopters had to stay above (IIRC) 1,000 feet until crossing Ocean Park Blvd. This made for an exciting approach, since there isn’t that much lateral distance to lose 1,000 feet. I remember splitting the needles once. Helicopters must ‘avoid the flow of fixed-wing traffic’ (U.S. rules). How they do it depends on local practice. At Van Nuys, the helicopter traffic pattern was 200 feet below the fixed-wing traffic pattern. Helicopters take off from the taxiway there, and have ingress and egress routes (e.g., ‘Tracks West’ – following the train tracks until clear of the airport). Flying into Fox Field, I made left traffic while the normal pattern there is right traffic. Instead of landing on the runway, I landed in a non-movement area (i.e., the ramp). Since the helicopters I flew typically made approaches at 60 or 70 knots – about what you’d do in a Cessna – some controlling agencies will integrate helicopters into the regular pattern. (Although as I said, VNY’s helicopter pattern was lower.) As **rsat3acr** said, a helicopter might make a pattern similar to fixed-wings, but turn at a different place so as to set down in an area more amenable to helicopter operations. Or a helicopter might land on the runway, as we did in training at Hawthorne Municipal when we were doing ‘full-down’ autorotations. Why not come in at height and descend vertically? That’s been answered by others. To reiterate, hovering takes a lot of power. That’s something you don’t have an abundance of in a Robinson R22 on a hot day in Southern California! More important is the height-velocity diagram (‘dead man’s curve’) **Richard Pearse** linked to. In normal operations, you want to stay within the envelope. Helicopters are unique in that they have capabilities that airplanes don’t. They frequently engage in ‘confined area operations’. This is demonstrated in Sporty’s [_So You Want To Fly Helicopters_](http://www.sportys.com/pilotshop/sporty-s-so-you-want-to-fly-helicopters-dvd.html) video, and is part of the training to earn a rotary-wing (helicopter) rating. Basically it comes to this: ‘Stay within the H-V envelope. If you need to fly outside of the H-V envelope, know that it is a calculated risk.’ Hovering is probably the hardest thing to do in a helicopter. It’s also the _first_ thing you have to learn. So once you have it, it’s no big deal. It’s not particularly ‘hard’ once you get it. One thing to watch for – and this relates to the OP – is the vortex ring state, or ‘settling with power’. This is a condition where the helicopter settles into its own downwash, and occurs when the machine is descending at greater than about 300 feet per minute and an airspeed of less than about 15 knots. Your own downwash is pushing you down. If you’re going down, you raise the collective, right? Nope. That just increases the downwash and you go down faster. You get out of it by flying (usually forward) out of it, or by lowering the collective pitch and flying out of it. You experience this in training – at a safe altitude. I think we practiced it at 2,000 feet AGL. Settling with power at a low altitude, such as trying to descend vertically to a landing, is not desirable. One of the helicopters were I flew was lost when the pilot settled with power and did not initiate a recovery in time. (He and his passenger were unhurt.) That’s where the ‘calculated risk’ comes in. If you _have_ to make a vertical descent into a confined area instead of making a normal approach (descent at approach speed, lower speed and descent rate, flare at about 40 feet, level about 8 feet, come to hover about 3 feet), settling with power is one of those things you’re going to pay attention to so as to remove that risk from the calculation. 😉 ---
**Author:** ![Dereknocue67](https://avatars.discourse-cdn.com/v4/letter/d/6de8d8/32.png) [@Dereknocue67](https://boards.straightdope.com/u/Dereknocue67)\ **Post date:** [December 9, 2015, 8:46am UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/9 "2015-12-09T08:46:42Z")
Airports have designated approach and departure flight paths to maintain separation and traffic control. Without aircraft following these rules, arrivals/departures would be chaotic. Imagine an interstate highway system allowing operators of more maneuverable vehicles to drive on either side of the road. There can be exceptions to this. I worked in a VFR tower with some helicopter traffic and sometimes a chopper pilot might request a nonstandard route. On slow days, no problem but with moderate to heavy traffic they follow the rules like everyone else. ---
**Author:** ![kferr](https://avatars.discourse-cdn.com/v4/letter/k/71e660/32.png) [@kferr](https://boards.straightdope.com/u/kferr)\ **Post date:** [December 9, 2015, 11:21am UTC](https://boards.straightdope.com/t/helicopter-landing-approach-question/739707/10 "2015-12-09T11:21:06Z")
I read the NATS document that **PaulParkhead** linked and found the VFR route for helicopters interesting: > [@NATS](#): > > EAST ROUTE: From/To the East: > Route from Worplesdon Station to Longerend Farm on the A324 and then to **Surprise Hill**. From Surprise Hill route west to join the Basingstoke Canal where it passes under the B3411 and railway bridges (Two Bridges). Follow the canal to the southern end of Queens Parade, then towards the Queens Roundabout for Runway 24 and Heli Bravo or towards the southern aerodrome boundary via the Army Golf Course for Runway 06 and Heli Yankee (See Notes 2 and 3) You wouldn’t think a Surprise Hill would be something you’d want to encounter when flying into an unfamiliar airport.