Helicopter/C172 interactions
 

After landing, I was cleared to taxi to base, crossing a taxiway. As I approached the junction I checked left and saw a helicopter coming down the taxiway at perhaps 20' above the ground. I stopped and let it pass in front. If I had not stopped we would have perfectly met at the junction.

I suspect the chopper was talking to tower while I was talking to ground - I certainly did not hear any radio traffic that might have helped.

That does not seem very satisfactory, what do you guys reckon? Could it safely had passed straight over the top of me with perhaps 10 feet clearance without any drama?

My first instinct would have been to visit the Watch Manager in the Tower upon shutting down, whilst the event is still fresh in everyone's mind. If you were 'cleared' to taxy, it implies full ATC. You mention Tower and Ground - this only occurs at very busy ATC aerodromes.
Worthy of a report to CHIRPS - GA section. They will investigate confidentially and report back if you feel the moment has passed or you don't want to discuss it directly with the ATC provider.

My personal view is that the downwash from a helicopter is equivalent to the weight of the machine. If that were to hit one of your wings, it could quite easily tip that wing to the ground. There's NO WAY, in my opinion, that a helicopter should hover-taxy over another aircraft. I'm surprised, actually, that a helicopter is taxying at 20' AGL.I'm not a helicopter pilot, but in my experience they normally taxy within a foot or so of the ground, in case the engine fails. At 20' there's no time to autorotate, I'd have thought.

In any event, you did precisely the right thing. If in doubt - STOP.

TOO

If, as TOO surmises, it was a controlled aerodrome, it should not matter if one aircraft is on GND and the other on TWR - the two controllers should have coordinated to ensure that the instructions passed to each aircraft assured safety and that suitable traffic information was provided. If you don't know or don't have a good relationship with the ATC people, or it's a few days since it has happened, I would agree that CHIRP is probably your best way forward.

Did you say anything to ATC at the time?

Yes it was a fully controlled airfield, andi it happened this afternoon. I did not say anything to ATC, on reflection I obviously should have done.

Thanks for your thoughts, I was not sure how serious it was.

That's a good point, I realize that I know nothing about how helicopters operate at this airfield. In fact, as I was lined-up to take-off for the same flight, I watched an aircraft back tracking while a different helicopter crossed the runway ahead of it. On this occasion the helicopter crossed well ahead, but I did not hear any radio conversation co-ordinating this crossing. In fact I took a picture of this rather strange scenario which I will attach here. But again the helicopter was very high for a hover taxi - if that is really what it was doing. On this occasion I was talking to tower as was the back-tracking a/c but I heard nothing from the helicopter so he could have been talking to ground which suggests to me that he was 'ground maneuvering', not 'flying'!

Perhaps I will ask around about helicopter operations. I am flying again today so could visit the tower and enquire.

https://cimg5.ibsrv.net/gimg/pprune....0f1ede3829.png
https://cimg0.ibsrv.net/gimg/pprune....2f3b8341df.png

Low flying over airfields
 

Any Rotorheads able to look at this thread:

https://www.pprune.org/private-flyin...eractions.html

I realize I don't know much about helicopter operations around airfields and what might have been going on in these incidents.

That is not a photograph of the 'incident'. That was a picture I took the same day while holding waiting for take-off clearance to illustrate the sort of height helicopters are moving around at. I had no problems with that situation there was masses of clearance all around everyone. I would be interested to know if you would consider that hover taxiing ?

If you check the 1st post you will see a description of a very much closer incident.

Worth a discussion with ATC to understand what clearances were issued. Helicopters are cleared to "taxi" on their wheels following taxiways/paved surfaces, or "hover taxi" at altitudes up to 25' AGL and 20 knots following taxiways/hard surfaces, or "air taxi" at altitudes up to 100'AGL (higher if requested) with speed at pilot discretion directly from one spot on the airfield to another. The helicopter is expected to avoid directly overflying other aircraft, buildings, etc.

It's Air Taxi or Ground Taxi on the ATC clearances - the difference between the two should be obvious and a skidded helicopter can only Air Taxi.

Most helicopter pilots understand exactly how FW operate so why do FW pilots not know about how RW operate?

I suggest you go and have a chat with ATC regarding heli ops at your airfield.

FW and RW pilots should fully understand the effect of downwash from a RW that can cause issues with light FW and plan their route accordingly.

RW will Air Taxi at anything between 5 and 20 ft perhaps higher if vacating from an approach to the runway - twin engine d helos will often taxi higher than singles.

Double barrel - you should have mentioned the potential hazard to ATC either at the time of by phone afterwards.

db,assuming you were lined up into wind,a nice,conscientious helo pilot would have crossed behind you,preventing his downwash drifting over you......

There are really 2 points here - one ATC and the other general respect for helos - dodgy blooming things ..... the latter that is!

For the ATC element, such situations are not uncommon at all - either with R/W or other F/W. Trust me - even the mighty ATCO's make the odd ".... erm, really?" clearances now and again! :ok: But we look out for their 6 just as I hope they are looking after our 6 so, if you spot a plan that seems not to be working, give the ATCO a "heads up" and shout out. The solution is usually quite simple in the sort of case you describe from an ATC point of view! You are Capt and, if unhappy, simply A-N-C - but always remember the last bit. When similar things have happened to me (and I probably sound like an aviating disaster area!!!) you do as you did. However, you have now effectively changed your clearance (I assume there was no conditional "give way to...." & you had a straight clearance) so you now need to tell ATC you have stopped as they are not expecting that - and your clearnace could be a small part of their "masterplan" involving others. I'd have said something like "G-AB holding short taxiway A - R/W traffic currently crossing ahead L to R.". No need for anything else - it's all that's needed - no drama, just fact. Note, it does not depend on who has right of way - assume you're the only one who has spotted it! This does 2 things - firstly tells any other aircraft (the one who is involved - if on freq - and maybe anything following close behind you) that you have stopped and, secondly, it alerts the ATCO that something odd is happening. Usually, after a grunt followed by an "Ahhhh....!" from the tower/ground/FISO, quick as a flash they will resolve it, not just for you, but anyone else involved by updating your/their clearance as required. In every case, I have had a call from the ATC once I've parked up just to thank me for alerting them! It's not just on the ground - I've even had things happen in the circuit - but clearly you can't stop tho you may have to take evasive action if you only spot it at the last second. But always "C" to let ATC know.

The bit about dangers of downwash, jet/prop blast and even just wind - always, always, always think and avoid. There was a dreadful case where a C182 (a really nice plane it was - and an even nicer family, sadly) landed quite legally at St Mawgan back in/about 2000 but then bounced and crashed and there was a Sea King in a hover (quite legally) quite some way from the runway. While it eventually transpired that the downwash did not cause or affect the crash, the subject of R/W downwash was discussed at length to see if it had had any affect and, as ever, some very useful sideline points came out even tho it was too far away to be involved. Sadly, the RAF dealing with the case was "suspect" in terms of the poor SK pilot.... but that's another matter for the Military forum - the SK pilot was, for a while, blamed ... but that is another topic. Back on topic, always think where you are and where others are (or will be!) WRT downwash and jet/prop wash - and, if in doubt, stop/avoid. A helo weighs quite a bit and all that downward thrust in a hover has to go somewhere - a nice little man*-made microburst! :} Experience helps but, in general, I view down/jet/prop wash as something that can really spoil my day! ;)

Just my thoughts! H 'n' H

* There are many lady helo pilots - don't want to be taken to task as being sexsist and all that jazz! :ooh:

I realize this is old fashioned...but both types of aircraft should show respect and courtesy to one another.

Helicopter pilots should remember the effects of their rotor wash and airplane pilots should understand the risks of that to their aircraft.

Giving way....using commonsense....to afford the maximum amount of safety to the other aircraft is not a bad thing.

Also, a very good idea is to actually study the Right of Way Rules and understand them....along with sharing a coffee with pilots of other types of aircraft and learn about them and how they go about their business.

One thing for sure....if you taxi in your small airplane underneath a hovering helicopter...especially one of some size....you will get one very quick lesson in physics, aerodynamics, and emergency medicine.

I am guessing that this happened in the UK and not the US. I can only offer the US perspective.

This could have been a failure on the part of ATC, the helicopter pilot, or both. If you were cleared to taxi as directed, that helicopter should NOT have been hover (5-10 ft) or air (higher than that) taxiing across your line of travel. Period. Dot.

Possible ATC failure: one or both of you were cleared to taxi improperly.

Possible helicopter pilot failure: he was cleared but did not act expeditiously, or he was not cleared to taxi as he did.

The only way to know is to query the ATC staff and find out what happened.

Regardless, you did some heads-up piloting and avoided any potential for disaster. You did the right thing. :D

Finally, it is worth noting that at helicopter-savvy airports it is not unusual for a helicopter to stay with the tower rather than switch to ground. This can be disconcerting to airplane pilots when they see a helicopter maneuvering around the airport but can't hear them on ground. This is a reasonable courtesy to the helicopter pilot who generally does not want to take his hands off of any control to change frequencies when in close proximity to the ground. While there are hardware and methods to do this, a single pilot without radio buttons on his cyclic or collective controls, or who has not programmed his radios for such controls, may plead "unable" to the tower when asked to switch to ground. The tower can insist, in which case the correct response is to set down, make the changes, and continue. But that rarely happens or is necessary (although it has happened to me!)

It's that equally old fashioned yet still 100% relevant notion called Airmanship.

Thanks all, very helpful, some clear learning points for me here. First, I take on board the strong message that I should have informed ATC - I confess it did not occur to me at the time; in my defense I was only stopped for perhaps 10 seconds or less. Also interesting to hear that a helicopter hover taxiing may be talking to tower not ground. I will spend some time listening to radio chatter and try to get a picture of how this is handled in my local area. And it is true that in all my theory and practical training the word helicopter has never been mentioned! That does look like a shortcoming.

It maybe worth mentioning that the geometry of the crossing situation made it very difficult for me to see the helicopter - in a high wing aircraft with the crossing taxiway at a slight 'backwards' angle the helicopter was high enough to be completely hidden by my wing in my normal seated position. Not until I leaned forward in my seat and checked the crossing taxiway did I suddenly see it alarmingly close.

To be completely honest, if it had been a fixed-wing a/c, I would probably have stopped, let it past and not given it another moments thought! I would have seen it sooner, and am well used to dodging stuff on the apron. The fact that it was to me a 'flying aircraft' made me question what was really happening here hence my original post.

Finally I would add that as a student pilot (I was returning from a solo cross-country) I expect every day to be a learning day and I am pleased that I posted here and made sure that I learned the right lessons!

Thanks!


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I was cleared 'Bravo to base'

All part of learning - never stops really! There is always a new curve-ball waiting to strike when you least expect it! :ok:

And SASless has it - just make time (especially if the Wx is worse than expected so you are in but not flying) to pop over and chat to others (mindful of the fact they may be busy doing other bad-Wx activities). Always a worthwhile exercise - even down to the point that, if operating mainly from one main base, you soon put faces/attitudes to voices on the R/T and know who you can start to trust when they are up there with you.

I just can't figure out why so many folk are always asking ATC for an emergency RTB as soon as I call for taxy! :p Just coincidence .... I'm sure .......

H 'n' H

Many rotor wing pilots also have fixed wing endorsements (including me) and understand the flow of movements on the apron. I see in the second picture there is an aircraft down the runway which looks like it's engaged in take-off. Chances are ATC cleared the helicopter in the picture to cross the runway and pass behind that aircraft, and had not yet issued you with a take-off clearance, which would be wrong as the other fixed wing aircraft was still very close to you.

I commend you for slowing down as described in your original post as it is better to be safe than be right and in burning hole. Safety is a two-way street, I too have been caught in hover just after take-off over a trolley burning dollar bills waiting for a slow coach fixed wing to taxi past so that I can enter the taxi way. Stuff happens and playing it safe always earns my respect than playing it arrogant.

No, that aircraft you can see down the runway is back-tracking towards me. I am holding for take off clearance. I knew I had plenty of time to pick-up my phone and take the picture of what i thought was an interesting scene, as the back tracking a/c had to come all the way up to the taxi-way where the helicopter is in order to exit the runway. It is a very busy airfield, and in fact that a/c had caused some annoyance/disruption to the flow by landing long on the crossing rwy necessitating the long backtrack of shame.

Depending on the age/fit-out of that AW109 helicopter it could cost between $1,900 to $3,500 USD / hour to operate commercially, the runway appears frozen while slowcoach backtracks in his $300 USD / hour Cessna along it, so why should the helicopter operator be punished if it can cross the runway safely - only takes a few seconds as opposed to minutes waiting for the slowcoach who caused the problem.

As mentioned before, better to always be safe than be right and in a burning hole, and I would not be surprised if ATC actually provided an expedited clearance for that helicopter's movement.