[Guyana, Dave Rohee] Overweight in a Twin Otter—but how?

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[Guyana, Dave Rohee] Overweight in a Twin Otter—but how?

Unread post by bimjim »

https://airfactsjournal.com/2021/04/ove ... r-but-how/

[Guyana, Dave Rohee] Overweight in a Twin Otter—but how?
APRIL 26, 2021

All the passengers were seated and my co-pilot walked through the cabin, making sure that everyone had their seat belts fastened. The ground crew closed the main door and gave me the thumbs up to start the left engine. Paul, my co-pilot, who I had flown with on many occasions, said, “Cap, everyone’s belted in, full capacity, and the manifest looks OK.”

I checked the instrument panel and made sure the right engine, which we kept running while on these short stops, was still within temperature limits and we had good battery power to start the left engine. Just before starting the engine, I turned to the co-pilot and asked for the manifest and load sheet that had to be approved and signed before takeoff.

Paul handed me the clipboard and said full cargo and passengers: eighteen passengers and 1,100 pounds of cargo. I checked to make sure the total reflected his words and that our maximum weight for takeoff did not exceed the limits of the Twin Otter series 200 we were flying. Max takeoff weight for this aircraft was 11,579 pounds. The load sheet showed the correct figure. However, the manifest sheet was a bit messy and smudged, but I was more concerned about the load sheet than the pax/load manifest.

The Ogle airstrip was not very long and mainly used by smaller airplanes and light twin-engine aircraft. It was owned and operated by the Booker Group of companies to maintain and serve as a base for its crop duster aircraft that fertilized the sugar and rice fields that dominated this location just east of the capital city, Georgetown.

Twin Otter
The Twin Otter can haul a load, but there is a limit.

Most of Georgetown and the East Coast of Guyana was at least nine feet below sea level. The Dutch, during their occupation of the country, had built a robust sea defense structure and aptly named “seawall.” The airstrip at Ogle was approximately one mile from the seawall. The land sloped away from the seawall and was quite a bit lower than 9 feet.

The airstrip was a narrow band of concrete 1,200 feet long and 30 feet wide with a grass overrun approximately 400 feet in length—not a typical type of location from which any airline would operate a Twin Otter. However, the Twin Otter, a STOL (Short Takeoff and Landing) aircraft, was quite capable of using this short airstrip. It was laid out with a row of hangars on one side and an open area on the other side. At the end of the runway, the land sloped gradually down to a low fence that bordered a narrow canal.

What made this location even more critical was the average temperature, usually between 90-95 degrees F, and very high humidity. I ensured that Paul had checked the small handheld engine power calculator that DeHavilland had included with the aircraft and asked for the maximum engine temperature for the takeoff. He read out the numbers we should be using as we taxied down the narrow airstrip.

I pivoted the airplane at the end of the airstrip and lined up for takeoff. We completed the takeoff checklist, and one last thought went through my mind: hot day, very humid, full load, and a short field! I was going to need a good takeoff run and slow climb-out to clear the seawall. I decided to use 20 degrees of flap to improve the short-field capabilities and shorten the takeoff roll.

I released the brakes and the aircraft started its takeoff roll. As the Twin Otter began picking up speed, the airspeed indicator came to life and showed a moderate increase in speed. Unfortunately, the concrete strip was disappearing at a rapid pace, and I immediately sensed that we might have a problem.

As I watched the airstrip quickly coming to an end and only the grass overrun available, I made the only decision I could: I jammed the throttles to the stops and prayed that we could make it over the fence. Thankfully, I had many hundreds of hours with short field takeoffs from my past bush flying experience, only in smaller and lighter aircraft.

The fear of running off the end of the airstrip was uppermost in my mind, crashing into the fence and ending up in the shallow canal, certainly guaranteeing severe injuries, possible death for everyone, and destruction of the airplane!

I felt the Twin Otter feel lighter and almost ready to fly. I slowly pulled back on the control yoke and eased the airplane off the ground. We ran out of concrete airstrip, and the aircraft left the ground sluggishly. We were not out of the woods by any means. The Twin Otter sank for a few feet after the takeoff but immediately stabilized, possibly from some type of ground effect updraft.

I distinctly remember a strange sight. As we were weaving through the area, I saw a woman hanging out her washing on her front porch, and she was actually looking down at the aircraft in horror as we went by!

I still had my hand firmly on the throttles, fully jammed up against the firewall. The co-pilot was now also looking outside and cried out, “Cap, the seawall—it’s higher than we are!” I did not even answer, concentrating on what moves I could make to get the aircraft to climb enough to clear the seawall.

We could not turn left or right as there were obstacles on both sides of the flight path, and we were now committed to flying straight towards the wall and hoping to clear it.

The Twin Otter had finally reached a minimum speed that allowed me some latitude to make a very slight backward movement on the control yoke. As I did this, I felt the aircraft achieve some minor lift, and I eased off a bit more flap.

Much of the surrounding area is actually below sea level—not helpful when you’re trying to climb out in an overloaded airplane.

As we got within a few hundred feet of the wall, I felt a small updraft, and I pulled back ever so slightly on the control yoke. The marvelous aircraft climbed a few feet, and we made it over the wall with a couple of feet to spare!

Now at least we were over the shoreline and only the ocean below us. The aircraft maintained a modicum of stability, and I felt the worst was over. I finally looked at the engine gauges and noticed that the engine temperature gauges were still in the red. I then looked up at the flap control and reduced it to 10 degrees and gently eased the throttles back from the firewall position.

The Twin Otter, great aircraft that it was, could only handle so much in terms of overload on a long runway with no obstacles. On the Ogle airstrip, this was almost a certain death sentence.

Before paying attention to the clipboard, I made a gradual left turn at a low altitude. The aircraft was still climbing but very slowly, and I still had the 10 degrees of flaps deployed. Then I looked at the load sheet. It appeared correct, and the total was at our all-up weight for the Twin Otter.

I then lifted the load sheet and inspected the passenger and cargo manifest. I immediately noticed something strange. Most of the passenger weights had corrections or were written over and looked as if they were changed. This situation bothered me, and I started looking closely at each of the listed weights.

I now saw a multitude of errors in the weights of passengers, and this may have extended to the cargo as well. I was pretty well pissed by this time.

I told Paul to radio operations and advise them we were diverting to Timehri. Tell them, “We had a malfunction and cannot proceed to our planned destination.”

I said, “Tell the dispatcher I need the aircraft to be met by the base manager, at least two ground staff, and a weight scale.”

The dispatcher seemed a bit confused! He said, “Please repeat the last transmission.”

I clicked the mike: “This is the captain.” I repeated the instructions and added, “I also want to park the aircraft away from the flight line as I need the passengers from this flight separated from any ramp personnel or other spectators.”

We got clearance to land and as soon as I reduced power, the aircraft started to sink. I applied enough power to arrest the sink rate. Paul called out the pre-landing checks, and we landed safely on runway 10.

After completing the after-landing checks, we taxied the aircraft to the Guyana Airways main terminal area. I called operations and told him to request an engineer to meet me at the airplane as I was concerned about the engine overtemp situation.

There was quite a reception awaiting us, including the base manager and some of the office staff. The ground crew was standing by a weight scale that is used to weigh cargo before loading onto aircraft.

I motioned to the base manager to come to the cockpit door. When he arrived, I jumped down from the cockpit and spoke quietly to him. “Andy, there was a dangerous mistake made at Ogle with the load sheet and the passenger manifest. I want everything taken off—passengers and cargo—and weighed on this scale.”

The base manager said, “You can’t mean that, captain? What’s up with the load and the manifest sheet?”

I said, “Andy, don’t doubt me. There are definitely mistakes in both the load manifest and the load sheet. And I intend to get to the bottom of this problem.”

The passengers were offloaded and weighed as they stepped off the aircraft. When I saw the last passenger had disembarked, I looked into the cabin and peered under the seats to make sure no one had left any bags. I noticed a lot of pipes under the seats and asked Paul to go into the cabin and tell me how long they were. He said that they were well over ten feet long and stretched most of the length of the cabin.

Paul said they were listed at 1,200 pounds on the manifest. I told the ground crew to offload the pipes and weigh them. The total weight of the pipes came to 2,200 pounds!

And when we were able to look at the passengers’ weights and compared them to the actual figures we just complied, we now knew that some numbers were changed to show a lower value. A shocking scenario and one that nearly caused the lives of innocent people.

When I calmed down in the flight crew ready room later, I was able to review the final tally of the passengers and cargo from the flight with Paul. The number of errors was staggering.

I was amazed that we were able to take off from the Ogle airstrip on a hot and humid day, well over 2,000 pounds overweight. Fortunately, we were able to live to tell the story.

Author: Dave Rohee

Dave is a retired commercial airline pilot with over 40 years of experience in all aspects of aviation. These include aircraft maintenance, bush flying, airline flight operations, corporate aircraft marketing and sales. Living in six countries in his lengthy career, he has experienced many adventures and misadventures, and a couple near tragedies during this period of his life.
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Joined: Tue Dec 04, 2007

Re: [Guyana, Dave Rohee] Overweight in a Twin Otter—but how?

Unread post by bushbai »

It's a fairly long way from end of runway to seawall.... Find that aspect a little suspect.

Unforunately had approx 1,000lbs overload on an Islander one time!!! and did not have a problem like that thankfully
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Re: [Guyana, Dave Rohee] Overweight in a Twin Otter—but how?

Unread post by bimjim »

After the last hurricane which devastated Dominica - it would have been before 1978 and before mandatory use of load sheets doing charters - I was taking VIPs into Canefield from Barbados with a BN-2A-9, with tip tanks. Back then we always filled all of the tanks every time because we never knew where the company would send us next, where we could get fuel, or where we would overnight, and with the copilot pedals and controls removed we could also carry a passenger in the right seat.

On this flight all of the (extended) baggage compartment was filled with canned goods (boxes), all of under the bench seats were filled with canned goods (boxes), and even the pedal well of the copilot seat was filled with canned goods (boxes). After fuelling we loaded 9 passengers, took off from Barbados and climbed to FL80, round the corner to Canefield on the west coast and landed to the south on only about 800 feet of available powdery rolled gravel with almost zero braking - the runway was still being constructed by the British, and there was a vertical drop-off into a ravine at the south end.

Landing was accomplished by very slow flight with max rpm, good power on, and stall warning blaring (as you know, the BN-2 stalls at 39 knots, but the warning comes on before that and the tip tanks probably give you a knot or two even slower), floating it just past the river and actually chopping power and dropping it onto the grass just before the gravel. I pumped the brakes all the way and came to a stop with just enough room remaining to add full power on one engine and turn before the drop-off.

Yes, daring (stupid?) days of youth, but I have to tell you that when I went to put pen to paper I calculated we were closer to 2,000 pounds over max gross on takeoff (and that version was 6,600 lbs MTOW) and I must confess that the aircraft took off, climbed, landed, and in every respect performed as though we were doing a _NORMAL_ flight somewhat _BELOW_ MTOW.

I have the greatest respect for the BN-2, in some 7,000 hours and over 10,000 landings on type I have been through some of the most violent turbulence, up and downdrafts and weather conditions, and it never let me down in any way. I also did the annual C of A flights for LIAT, and - loaded up to MTOW with photocopy paper - they did descend from the starting 6,000 feet on one engine under C of A specs, but settled down to level flight at its own safe single engine altitude capability.

A fine airplane, and fine engines. Respect.
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