Or why I won’t do aerial photo/video flights with three passengers on board.
It’s that time of the season again: time to go through the NTSB reports to see how and why helicopters are crashing. As I’ve mentioned elsewhere in this blog, it’s usually due to “stupid pilot tricks.” Here’s yet another example.
The full narrative is a bit lengthy to quote here, but I’ll summarize:
R44 Raven I helicopter with four people on board. The pilot estimates the weight of the aircraft at the time of the accident was 2,391 pounds — just 9 pounds less than max gross weight for that aircraft. The accident occurred 25 to 30 minutes after takeoff. If the aircraft burns 15 gallons per hour (as conservatively estimated by Robinson), it burned at least 7 gallons during the flight. 7 gallons x 6 pounds per gallon = 42 pounds. So yes, the helicopter was over max gross weight at takeoff. No wonder the pilot “was concerned with the density altitude at the departure airport.”
Speaking of density altitude, the temperature was 31°C at the closest weather station, which was 12 miles away and sat at 4,964 feet. The calculated density altitude was 7,721 feet. The wind was 17G32.
The purpose of the flight was aerial photography. As any commercial pilot can tell you, that often means low and slow flights. So slow, perhaps, that the helicopter began to settle (under power) during a turn about 100 feet above the ground. There was a close call with two sets of power lines, which the pilot was able to clear while the low rotor horn blared. But the pilot was unable to gain enough speed and keep enough altitude to prevent settling into the ground. The helicopter rolled and three of the four occupants received minor injuries. The helicopter was totaled.
A look at the performance chart for an R44 (Raven I) makes it pretty clear why the pilot had trouble maintaining altitude at slow speed. At max gross weight on a 30°C day, the helicopter can’t even perform an out of ground effect (OGE) hover at sea level, let alone nearly 5,000 feet. That means it would have to continuously fly above ETL (approximately 25 knots airspeed) to stay in the air. At slow speed, a turn into a tailwind situation would rob the aircraft of airspeed, making it impossible (per the performance data, anyway) to stay airborne.
(It’s important to note that the R44 Raven II helicopter has much better performance at high density altitude. That’s why I paid the extra $40K to buy a Raven II instead of a Raven I.)
How could this accident have been prevented? Lighten up the aircraft. One way is to take just the passenger with the camera. Leaving two passengers behind would likely have lightened up the aircraft by 300 (or more) pounds. According to the OGE hover chart, at 2,050 pounds, the helicopter could (barely) hover out of ground effect. But even in that situation, the high density altitude would have made the helicopter sluggish and limited its performance. While an experienced pilot may have been able to pull it off, not every pilot could.
But this doesn’t excuse the pilot from doing his homework. A quick look in the pilot operating handbook (POH) would clearly show the aircraft’s limitations. The chart is in there for a reason.
Still, I could put myself in the pilot’s shoes and envision his situation. He knows density altitude could be an issue. But there are three guys and they see a helicopter with three empty seats. Why can’t they all fly? The pilot does a test flight with two of them on board and doesn’t have any trouble. What’s one more person, the passengers ask. Joey really wanted to come, too. The pilot succumbs to the pressure of this passengers and does something he knows deep down inside is probably very stupid.
And he pays for it.
How many times has this happened to you? Once?Twice? Ten times? I know that some version of this has happened to me. Every time it’s happened, I walked away without any problems. But during the whole flight, I worried. I knew what could happen. And I was relieved when things didn’t go wrong.
Is that the way we should be flying?
Hell, no!
Now I personally have a hard and steadfast rule: maximum of two passengers for aerial photo/video flights — preferably just one. And if I don’t feel like I have enough reserve power under the flying conditions — keeping the OGE Hover Chart in mind — I won’t do any hovering or very slow flight.
In my opinion, it’s not worth risking the safety of flight just to make a client happy.
Think about this the next time you’re preparing for an aerial photo mission.
Good comments Maria. I have over 10000 hours in all sorts of helicopters and weather conditions, and one doesn’t last that long by ignoring the performance data of your machine
Density altitude is something that fascinates me. Many, many helicopter accidents are caused by pilots overestimating the performance potential of a helicopter at high density altitude. The charts don’t lie — but the pilots either don’t consult them or they ignore them. In a lot of instances, the pilot is simply not accustomed to operating at high DA and assumes the aircraft will perform as it does at lower elevations. Often it’s lack of experience that makes an overconfident pilot do something dumb. In too many cases, the pilot does something dumb because he’s pressured by passengers who don’t understand the risks. I can’t tell you how many times I’ve had aerial photo shoots where the passenger tried to insist that we fill all the seats because he was paying for them. I used to cave in but I don’t anymore. I’d rather not do a flight at all than to do one that I’m either questioning the safety of flight or not able to perform the maneuvers the photographer needs. I blogged a bit about how nice it is to fly with professionals here: https://travelswithmaria.com/2013/09/14/the-joy-of-flying-with-an-experienced-professional-videographer/
Anyway, I need to do another blog post to explain why I always refer to the OGE hover chart rather than the IGE hover chart. Maybe later in the week.
Thanks for taking the time to comment!
While some of what you wrote is technical, even my non-pilot brain gets the gist of all this. Bottom line to me is that safety must come first, and if some don’t get it, well, too bad… you’re the experienced pilot, after all. :-)
Exactly. It’s when inexperienced or overconfident pilots are too eager to please that things can slip into the danger zone.
How many times when two seats were scheduled and three or even four showed up did I have to give the speech. Yes, the JetRanger can hold 100 gallons of fuel and can fly for four hours. It can fly up to 150 miles per hour and it can carry five people. It can hover a mile above the ground and it can fly with all the doors off. Yes, it can fly backwards. But it can’t do all of those things in the same configuration. Yes, I have to configure the helicopter for the mission that you want to accomplish. The helicopter is versatile and can do a lot of things but everything requires a trade-off. More passengers requires less fuel, no hovering, no downwind turns. More maneuverability requires less of everything else. If you want to take your friend, you won’t be able to get the pictures you want. Most people don’t understand all that and have to be educated. A lot of people hear what the pilot tells them, but aren’t really listening.
Well said. They look at the top end of all the specs they have access to and become convinced that the helicopter can deliver them all at once! Never thought of it that way, but it certainly applies!
Always good to be reminded. Flying a 300C in CO at 5000 MSL on hot summer days has given me a good taste of those limitations. Weighing 115 allows me to fly when the other guys weighing 70-80 pounds more are grounded. But I don’t take advantage of that. It is a training flight and not worth any risks. Flying with a student is risky enough. Why push it and fly on a high DA day and have any of those heart pounding moments happen. I don’t want to create an extreme situation in a training flight. Bumping up against it once or twice has given me the awareness of how easily it can happen. Even when you have checked the charts and planned accordingly. In my opinion, Robinson’s charts are gracious and more true where the 300 not so much. The chart may say your good to go, but finding that isn’t always the case. So I use the charts, know the expected limitations, but also plan for the unexpected limitations so that I’m not taking anything for granted.
Bumping up against the performance limitations is a good way to really get a feel for the aircraft and learn about what it can or can’t do. The smart pilots will bump gently and learn; others will push hard and have more painful lessons.
The day prior to your posting this article I flew a photo mission near Lewiston, ID, with four souls on board (two camera operators and the client). The only reason the pilot allowed four passengers was the fact that the OAT was 35 to 40 degrees and density altitude was near sea level with minimal winds.
As a pilot and aerial photographer/cinematographer of twenty-odd years experience, I am both concerned and considering on each mission whether the load will exceed aircraft capability. I very seldom fly in helicopters with any other persons besides myself and the pilot unless the job absolutly demands both still and cinematography.
Personally, I rarely (unless it can’t be helped) ask a helicopter pilot to hover OGE. I prefer to maneuver—at the pilot’s discretion—at ETL plus 5 knots. In my experience that airspeed renders the least vibration in the airframe and a pleasing rate of change in the perspective. Unless of course, for safety’s sake, atmospheric conditions demand higher airspeeds.
Thanks again Maria for a insightful, honest and erudite article. I will keep your thoughts in mind on the next mission.
Thanks, Ken. I really don’t like hovering OGE and will avoid it whenever necessary. But it’s very doable on a cold, calm wind day with just two people (me and the photographer) on board. I was even able to do it once at Bryce Canyon (8,000 feet MSL!) — but that’s because it was -7°F out. (Not the kind of day you want to be out with a door off.)
I really like working with photographers who understand the limitations of the aircraft. It makes photo missions a real pleasure. Thanks again!
Thank you, Maria. As a photographer it’s a much easier aerial photo mission when the pilot either understands photography and/or is also photographer. Those missions, for me, always seem to go smoothly and produce the best results.
I do some photography, but can’t really consider myself a photographer. Still, I know what’s needed to get the shot. I like when the photographer sits behind me so I can see what he sees. I require that for air-to-air missions.
You should understand that servo transparency is a natural phenomenon for any flyable helicopter. BASIC AIRMANSHIP should prevent encountering this phenomenon by avoiding combinations of high speed, high gross weight, high‑density altitude, and aggressive maneuvers, which exceed the aircraft’s approved flight limitations.
The helicopter’s Pilot Operating Handbook (POH) has both In-Ground-Effect (IGE) and Out-of-Ground-Effect (OGE) hover charts. This allows the pilot to take the density altitude and gross weight into account to predict hover performance. It is very important for pilots performing some missions such as ENG (Electronic News Gathering) or external lift operations to know if their helicopter can hover out of ground effect. Safe helicopter operations depend on good performance planning.