This article is a little bit of a cheat because nothing went wrong (thankfully) but it's still interesting in my opinion.
Our aircraft usually does not require us to do a weight and balance calculation: if we fill the tanks to the tabs (not full) giving 4 hours of flight time, and we have up to 4 normal adults with zero luggage, then everything is usually within limits.
I planned a flight to Walney Island (Barrow-in-Furness) and then on to Oban in Scotland. We were to stay with friends in a quaint little village called Leece near Ulvaston and take my friend's husband and son on a flight around the Lakes whilst there. Our friend's husband, who I am avoiding naming for reasons you'll see below, would travel up with us - let's call him Mr. A.
|So, in the aircraft I had planned myself (13 st.),
my wife (9.5st.), my granddaughter (2.5st.), Mr. A (guess 15st) and
luggage of 20lbs. Fuel at tabs is 4 hours @ 34 litres per hour = 216lbs.
This put the aircraft at MTOW with CofG ok.
At the last minute Mr. A. asked: "what's 15st in Kgs?" I replied "approx. 95." He replied: "you need to allow at least another 10!!".
10Kgs at a rough estimate is 22Lbs so that made our luggage allowance -2 Lbs!!! My wife said that 20Lbs was on the short side in any case considering we needed a push chair and a car seat so she weighed the luggage and it came to 30Lbs.
So we needed to save 30Lbs plus the 2 Lbs short making 32Lbs. The only way to do that is to lose fuel. We were already tanked up so I'd have to fly off 21Ltrs of fuel before leaving!! A real pain.
Now although we would still have sufficient fuel to reach our destination and our alternate (Blackpool), Walney Island has no AVGAS which meant we would not have sufficient fuel remaining to fly to anywhere to refuel (allowing again sufficient for an alternative). So we'd have to stop at Blackpool on the way and top up. However Blackpool is an international commercial airport and we could not get straight answers from them as to whether we would have to pay handling fees on top of landing fees, how long the turnaround time would be to fuel up and take off again etc.
Even topping up at Blackpool, there would still be insufficient fuel remaining to do the Lakes tour so we'd have to fly to Carlisle to re-fuel again before doing the Lakes trip.
By this time we had abandoned the idea of Scotland, but noted that after the Lakes trip there would be insufficient fuel to fly home again - we'd have to revisit Carlisle and re-fuel one more time.
The final straw was the forecast of heavy rain at our start point with possible thunder CBs over the Pennines.
We decided it would be stupid to risk flying in poor weather loaded up to MTOW and stressed out by all these fuelling stops.
In the end we went by car.
We will still do Walney Island in the summer but Mr. A. can go by car, we will fly there on full tanks, and we'll have enough to take him sight seeing over the Lakes and still have enough to fly back to Nottingham again.
The key messages here I think are: never guess the weight of your friends - always check; in general add another 7Lbs to cover clothes since they might weigh themselves normally out of the shower; don't forget in the fuel/weight calculations to leave enough for an alternative destination; if you don't like the look of it then don't fly. Mr. A., whilst disappointed that we didn't fly, was at least reassured that I had done such detailed calculations and had no intention of merely assuming his weight - I needed to know for sure.