Go Back  PPRuNe Forums > Aircrew Forums > Rotorheads
Reload this Page >

EMS Very Slow approach - why?

Rotorheads A haven for helicopter professionals to discuss the things that affect them

EMS Very Slow approach - why?

Old 8th Jan 2013, 00:01
  #1 (permalink)  
Thread Starter
 
Join Date: Jan 2012
Location: Central Coast, CA
Age: 41
Posts: 13
EMS Very Slow approach - why?

I was just curious why every EMS helicopter I've seen seems to slow to almost HOGE and do a really slow, increasingly steep "parabolic" approach. It's stable, controlled and looks safe, but I was just wondering if maybe someone could describe in detail what that approach is all about.

I've wanted to re-create that kind of approach in training, but the instructors I've had bark when I get slower than 30 kts if not within 30' of the ground (which feels way faster than "walking it in").
Runon is offline  
Old 8th Jan 2013, 00:11
  #2 (permalink)  
Thread Starter
 
Join Date: Jan 2012
Location: Central Coast, CA
Age: 41
Posts: 13
I'm of the opinion (because people argue this all the time) that you can't stabilize anything steeper than 30kts 300 fpm without slowing down first

- or using a "skijump approach" (30kt/300+fpm - flare 30/0 to 0/0 and descend pretty much IGE).

I just don't get it.
Keep in mind this is a question, not a statement.
Runon is offline  
Old 8th Jan 2013, 00:31
  #3 (permalink)  
 
Join Date: May 2002
Location: "Deplorable but happy as a drunken Monkey!
Age: 71
Posts: 16,431
It gets you slow....gets the power in....gives you lots of time to look for wires, obstacles, and if landing to a roof top allows you to get to the deck if an engine quits.....or so it was explained to me years ago by an Operator i worked for.

I saw it as prolonging the agony if something were to go wrong.

I do agree with a steep approach but with a normal rate of descent rather than the very low ROD as is used by some of the Operators.
SASless is online now  
Old 8th Jan 2013, 03:19
  #4 (permalink)  
 
Join Date: Apr 2003
Location: USA
Posts: 41
Multi-engine helicopter or single engine?
havick is offline  
Old 8th Jan 2013, 04:05
  #5 (permalink)  
 
Join Date: Oct 2004
Location: USA
Posts: 217
Even with a single engine machine it is a generally safer approach (especially at night) when landing to unimproved areas. Your chances off hitting a wire or other nearly invisible obstacle are much greater than your chances of having an engine failure. Power should not be of any issue since you are planning to to pick up 200 pounds or so and accomplish a nearly verticle take-off if it is a scene response. Less than 30/300 should keep you clear of settling. You have nearly hover power applied and a very slow descent so if you see something you don't like, a go-around can be accomplished with nearly ZERO further descent or delay. You will be above any dust/snow cloud so you will not be surprised below the barriers, and will have the option of continuing the approach, stopping to a hover to see if the obscuration dissipates, or go-around and plan a new course of action.
Not being in a hurry is usually to your benefit.
mfriskel is offline  
Old 8th Jan 2013, 04:32
  #6 (permalink)  
 
Join Date: Jul 2001
Location: ...in view of the 'Southern Cross' ...
Posts: 1,378
Mmmm ....

AND I really think you'll find that the 'parabolic approach' isn't that at all ... but a well defined constant angle varying airspeed low(ish) rate of descent requiring minimum power changes till committing to the hover ...

Sometimes you might even have a crew member with their heads out the door checking and clearing your tail ... the communications for which will require time ... you don't want to be doing that stuff in a hurry ... THAT IS how incidents can occur ..


Last edited by spinwing; 8th Jan 2013 at 04:32.
spinwing is offline  
Old 8th Jan 2013, 09:04
  #7 (permalink)  

The Veloceraptor of Lounge Lizards
 
Join Date: Jan 2005
Location: From here the view is lovely
Posts: 339
Sounds exactly like a Class 1 heli-pad approach as specified in the AFM.

I fly the 135 and our ops manual says that ALL approaches to confined areas shall be flown to the Class 1 profile (EC135 LDP 120' IAS 30kt ROD less than 400' per min) In the event of an engine failure after LDP the landing even at RTOW is assured. The take off is basically the same thing in reverse (TDP 120 ft, ROC 200-300' FPM keeping the landing area in sight at all times)

I can understand why your instructors bark when you try it, if your'e in a single engine aircraft it will stick you (and the long suffering instructor) right in the avoid curve, while a lot of utility pilots spend a lot of time in the avoid curve many instructors are a tad concerned at being in the curve with a low hours student in control, an engine failure there will pretty much guarantee a broken helicopter and occupants.

VH
verticalhold is offline  
Old 8th Jan 2013, 09:37
  #8 (permalink)  
 
Join Date: Feb 2010
Location: Honiton, Devon
Posts: 20
We run a 135 as well on a yacht, moving platform most of the time, and all our approaches and departures are Class 1. Our pad is the minimum dimensions the designer could get away with (but fully rated - never have worked that one out!!) and plus we normally have turbulence from the accommodation and heat from generator engine exhausts to contend with.

As a side bar I saw an EMS 135 in Devon a few years try to land in a field next to a car & motorcycle accident and he had to bail out as it was too steep, and then only place left to land was on the road in a very tight area with cables and trees all around him, weather was very severe almost gale conditions, he tracked down the road towards us, down a hill, with tail into wind and slashing rain, plonked it right in front of me. The best bit of flying I ever seen!! In from high and fast with a fancy flare was never going to work that day!!
CaptainSAC is offline  
Old 8th Jan 2013, 20:46
  #9 (permalink)  
 
Join Date: Oct 2003
Location: Over here
Posts: 1,030
I try to guard against the most likely bad occurrence. At an airport or prepared heliport, where I'm sure there are no wires, I do a faster approach, but to an unprepared scene, where the likelihood of unseen wires is greater than the likelihood of an engine failure, I make a very slow approach, at least for the final couple of hundred feet. There are wires everywhere, and they can be almost impossible to see until you're within a few feet of them. Making the approach slow enough to allow stopping to a hover, and then climbing back out, gives me the best chance to avoid wires. I don't like vertical takeoffs, but doing one from a scene is safer, IMO, than trolling for wires on a normal takeoff. Playing the odds gives me the best chance of surviving and making another flight, and the odds favor slow, steep approaches and vertical takeoffs from unprepared scenes. From a runway, obviously a normal takeoff staying outside the avoid area of the h/v diagram is safer, and that's what I use when I can. It all depends on the situation.
Gomer Pylot is offline  
Old 8th Jan 2013, 20:55
  #10 (permalink)  
 
Join Date: Jun 2012
Location: North America
Posts: 20
Post The Survey says.....

to avoid settling-with-power.

I asked a BK117 HEMS pilot that question years ago and his answer was he wanted to avoid settling-with-power.

Last edited by OffshoreHeli-Mgr; 8th Jan 2013 at 20:58.
OffshoreHeli-Mgr is offline  
Old 8th Jan 2013, 22:44
  #11 (permalink)  
 
Join Date: May 2002
Location: "Deplorable but happy as a drunken Monkey!
Age: 71
Posts: 16,431
At night doing takeoffs from Scenes....I pointed the Landig Light, Search light, and Night Sun up nearly vertical and flew up the light beam to make sure I did not run into any wires. The risk of an engine failure was far less than that posed by a wire strike.

Likewise at night I made steep, slow approaches using the lights in the same manner but pointed downwards and tried to stay along where the lights were shining.

That was in the Bell 412/BK-117/BO-105....so we had plenty of power and lots of light.

I would not do EMS flying at Night in a single.....there are plenty of jobs available so one does not have to do that. (Personal Opinion thought it is!)
SASless is online now  
Old 9th Jan 2013, 16:26
  #12 (permalink)  
 
Join Date: Apr 2000
Location: EGDC
Posts: 7,565
Doesn't anyone recce the LS in an orbit or from the downwind leg at low level to check for wires and things any more? Looking at the site from more than one angle gives you far more opportunity to see those hidden wires and select the best point to make the approach to.

This is how we tend to do it at night as well.

Last edited by [email protected]; 9th Jan 2013 at 16:26.
crab@SAAvn.co.uk is offline  
Old 9th Jan 2013, 17:26
  #13 (permalink)  
 
Join Date: Oct 2004
Location: USA
Posts: 217
Lots of things can surprise you on final after a few turns around the LZ reconnoitering your heart out. I am sure you have never had a surprise at 2AM. Set yourself up for success and with luck you will never have to use your back-up plans.
mfriskel is offline  
Old 9th Jan 2013, 21:31
  #14 (permalink)  
 
Join Date: Oct 2003
Location: Over here
Posts: 1,030
Of course we do low recons of the LZ. But I never, ever bet my life on being able to see every wire from a few hundred feet up, while moving at >70mph. Powerlines and telephone lines can be very small, and difficult to see while standing directly under them. I know the firefighters on the ground have looked for wires, but they can miss them, and do. Making a couple of circles and then a normal approach, assuming you've seen every possible wire, will kill you eventually.
Gomer Pylot is offline  
Old 9th Jan 2013, 21:36
  #15 (permalink)  
 
Join Date: May 2002
Location: "Deplorable but happy as a drunken Monkey!
Age: 71
Posts: 16,431
Crab,

I have as strong a desire to live as the next guy....and did my utmost to avoid a premature departure for where ever I am bound when I do....but I have had some very close calls.

Put the wooden poles back inside the wood line....stretch a wire or wires between them over a roadway....and see how easy it is to miss seeing them at night....even with all sorts of lights shining down on them and Fire Fighters doing a ground Recce for you to boot.

Put a nice skinny radio mast up near a hospital landing pad.....and not put any markers or lights on the guy wires.....see how quickly they disappear.

I have almost run over wires in the day light drying Cherry Trees....which is nothing more than a low forward speed HOGE exercise. Some of the wires are damn thin and skinny.

Every one does a good Recon at night....sometimes it is three orbits around the LZ or more even.....No sane person does a single downwind oogle of site and then does the confirmation on finals....and lives to be an old man anyway.
SASless is online now  
Old 9th Jan 2013, 22:24
  #16 (permalink)  
 
Join Date: Sep 2003
Location: Redding CA, or on a fire somewhere
Posts: 1,718
I am with SAS... Wires are difficult to see. In order to fly for PG&E and WAPA, all of my pilots are required to complete annual training on "Flying in the wire environment". The initial course is TWO full days...... Before attending, I thought the same as most---how do you fill 2 days on wires....? I now do the annual one day refresher every 12 months and still learn new stuff on how to detect wires.

If you have not seen it, this is worth a watch:

Gordy is offline  
Old 10th Jan 2013, 01:23
  #17 (permalink)  
Thread Starter
 
Join Date: Jan 2012
Location: Central Coast, CA
Age: 41
Posts: 13
You all have been absolutely ..... AWESOME!!!!
Thank you very much for the participation, the thoughts and most importantly taking the time to discuss this so that I (And I'm sure a lot of new or young pilots) can think, discuss and most importantly LEARN from your experiences.

I know it sounds a little .... I don't know .... wierd, but the stuff I read on these boards are sometimes the voices in my head when I'm approaching questionable situations.

Thank you guys very much.
Runon is offline  
Old 10th Jan 2013, 01:34
  #18 (permalink)  
Thread Starter
 
Join Date: Jan 2012
Location: Central Coast, CA
Age: 41
Posts: 13
You make a really good point spinwing - I've never actually tracked one all the way down, my imagination actually kind of filled in the vague spots so I can tell you definitely .... that I wasn't quite positive it was "parabolic".

BTW - how come the firefighters don't hose down dusty LZ's? (or do they?)

Last edited by Runon; 10th Jan 2013 at 01:35.
Runon is offline  
Old 10th Jan 2013, 02:33
  #19 (permalink)  
 
Join Date: Sep 2003
Location: Redding CA, or on a fire somewhere
Posts: 1,718
Runon

BTW - how come the firefighters don't hose down dusty LZ's? (or do they?)
We do:

Gordy is offline  
Old 10th Jan 2013, 07:55
  #20 (permalink)  
 
Join Date: Apr 2000
Location: EGDC
Posts: 7,565
I didn't say stop looking for wires on final approach but you don't have to make slow, steep approaches to avoid wires - certainly those of you who have operated in a tactical environment won't have done that.

I cut my professional teeth in Northern Ireland where every field has wires but we still managed to get in and out quickly without taking any out, day or night.

The suggestion that you have to do a very steep and slow approach to be safe is erroneous and misleading.

Yes there are always the telephone wires in the tree-line and the little whip mast hiding but a low-level recce at relatively low speed and height plus vigilance on finals (if you have picked the clearest approach path) will keep you safe 99% of the time.

There will always be the really tricky LS where there are so may obstructions and such a small area to land that a high hover and vertical or steep approach will be required but there is no need to use this in every case as some people here seem to be suggesting.
crab@SAAvn.co.uk is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.