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The six Ps.

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Aug. 31st, 2016 | 03:14 pm

The six Ps: Piss Poor Planning Prevents Proper Performance.

Better put: Plan to succeed, and your plan will succeed.

One of the things we're taught (and it's true!) is that everything in a helicopter is a tradeoff.  We use lightweight materials because heavier ones cost more to lift, hover, suspend, and move.  We use the smallest engine that will work for the same reason.  We take the minimum necessary fuel+reserve to do the mission for the same reason.

In fact when planning a flight, having reviewed all the external paramters like weather, forecast, TFRs, NOTAMs, charts, etc., it's crucial to calculate several things.  We do a planned flight to figure out fuel burn and then figure fuel loading and weight.  We then do a load calculation to figure out how we fare compared to maximum take-off weight (MTOW).  Then we do a center of gravity (CG) calculation to ensure that at the start of the flight (full fuel) and end of the flight (only reserve left) we are still within the manufacturer guidelines for proper CG.

In addition to those hard rules, we also have some other rules we use.  One of them is "performance is affected by loading so minimize your loading."  Our biggest loads are passengers and fuel.  While we can't slim down the passengers, we can plan for minimum necessary fuel to complete the mission.  That means if we're planning for a 1.0hr flight, load up fuel for 1.333hr (1.0hr flight+20min helicopter day VFR reserve).

On today's flight I was flying a photographer who takes pictures of 25-27 sites throughout the Tucson valley and surrounding area.  Usually it takes 1-2 orbits to get all the shots he needs of each site, and we're off to the next.  The typical flight time has been as low as 46 and as high as 56 minutes.  For this flight the winds were 16G23 (16 knots gusting to 23 knots) so figuring we'd be working against the wind half the time I budgeted for more fuel and took on enough for 1.5hrs.  The photographer is a light person and there were only two of us, so I could have put more in but was minimizing weight as per standard operating procedure.

As we started doing the orbits we needed more work to get the pictures.  The wind wasn't just pushing us away on the one side and closer on the other, but because the aircraft was pointed mostly toward the wind ('in trim') we just didn't have 90° shots from all four sides.  Eventually though we got them all.  Over time that extra orbit here and there added up and I started to watch as we hit an hour of flight time and still had a few sites to do.  The site before the last is the furthest out... and then we cut 20 miles across the desert to the last site... and then 20 miles back to the airport.  With the door off for the photographer our speed is limited by the factory recommendations to 100 knots, so that is 24 minutes of cruise for those 40 miles.

As we headed southwest to the last site we passed a construction site and the photographer wanted to do that one too... but being concerned about our airtime vs fuel I said we couldn't afford to do it.  As it was not on his list (nor was he getting paid for it) he was fine with that.  We cruised across the desert toward the northern side of the Tucson Mountains.  As we crossed, the wind compressed between the hills hit us like a hammer and I had to yank us back from 100 knots to about 60 while the clutch belts tightened after the main rotor experienced the hit as well.  That was the only real turbulence we felt but yeah we felt it.

At that point we were three miles from Marana Regional Airport (KAVQ) and I pondered the possibility of stopping there for some AVGAS.  Sure, we'd lose 30 minutes, but it would remove any question of sufficiency of fuel.  In the end I decided that as we only had one site to do we should be fine.

We hit the last site immediately, he got the pictures done in 1.5 orbits, and we headed toward Tucson.  Since I'd mentioned the fuel when rejecting the construction site, he noticed the needles were getting really close to the E.  I pointed out the low-fuel light and said that when that thing came on we'd still have 20 minutes (give or take) and we were showing 12 minutes to the airport.  However, that's because had we flown line-of-sight it would have been 12 minutes.  In reality we had to go east to cross back to the east side of the Tucson Mountains, and that meant that for a good 5-7 minutes it remained showing 12 minutes to the airport while we transitted the mountains.

Finally on the east side, we picked up Tucson ATIS and called Tucson Approach.  They had us IDENT and located us on radar.  They directed us to A-Mountain which was conveniently right along the direct flight path so no objections came from us, and then they turned us over to Tucson Tower.  Tower was equally accommodating, advising us to proceed direct.

A couple of minutes later, with 7 minutes showing enroute to Tucson the low-fuel light came on.  I let the photographer know that we were well within parameters.  We then flew in at top speed, and did the fastest approach I've done in a while.  Soft set-down, called tower to let them know landing assured, and proceeded to do the cooldown.  The cooldown proceeded for 2+ minutes and I shut the engine off when that was over, never having ran out of fuel.

There was no accident or incident here, but there certainly was an educational event.  I made a series of judgment calls that could have led us into a serious situation.  These led me to reflect on how to better handle this next time -- not just for photo flights, but in general.

1. We've been taught to always take on minimal fuel for the mission plus the reserve.   Going forward I'm gong to take maximal fuel to keep us right below MTOW unless we need high density-altitude (DA) operations requiring a lower weight.  (For example, in-ground-effect (IGE) hover can occur at higher DAs with lower weights).  That means that for this flight instead of taking less than 2hrs of fuel, I'd have taken the full 3hrs of fuel (depending on altitude, pressure, humidity, etc.)

2. When fuel is low, DO DIVERT TO A NEARBY AIRPORT.  It would have been a one-time cost of 30 minutes of my time to divert to Maran (or Pinal Airpark, KMZJ) but I didn't make that choise.  Next time I will not take that risk and I will do the safe thing.  Safety first is not just about "on the ground" or "in the air" but also about resource planning.

3. When a strong wind is in effect, add a wind-factor to expected times.  Particularly in a photography situation where we can't just orbit and keep the body of the aircraft perpendicular to the target, it will take longer to do the shoot.  Also as half the time we're in a headwind and half in a tailwind, but you can't win back in a tailwind what you lose in a headwind, remember we are going to be
effectively traveling SLOWER.

I have worked with some excellent certificated flight instructors (CFIs) and they have taught me a lot.  It would be nice if I could return the favor by letting them know that as they instruct other "newbies" they should focus on these real-world situation.  It could waste someone's 30 minutes or so... and gain them a lifetime.


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