Weight and Balance

Is Weight and Balance Really that Important?

A Beech 1900C (Be 1900) prepares for departure from Kodiak, Alaska, on a clear November day for a multi-leg flight and the First Officer (FO) requests 1500 pounds of cargo accompany the 19 passengers.  The agent notes the amount of cargo is unusual, compared to other pilots flying the Be 1900 with a full passenger load.  He didn’t ask any questions?  In fact, this violates a company policy of loading only 1100 pounds of cargo with a full passenger load.  Neither one knows the policy?  With the forward baggage area at capacity of 250 pounds and 1250 pounds in the aft cargo compartment, the center of gravity (CG) would be 3.5 inches aft of the limit.  Think this is why the 1100-pound policy is in place?

The baggage loader noted the tailstand was only about an inch from the ground after the cargo was loaded.  He had never seen it lower than 3 to 4 inches.  If the purpose of the tailstand is to prevent damage to the aircraft, in the event cargo loading causes it to tip onto its tail, does this not warrant pointing the small clearance out to the agent or flight crew?

Surely, the weight and balance sheet will catch this.  The ground crew completes the flight log using memorized cargo weights and informal worksheets, which indicate the cargo weighs 1450 pounds.  What’s an informal worksheet?  Wait, did that say “memorized cargo weights?”

As the flight crew fills out their manifest during startup, it does not include cargo.  Did they forget about the 1500 pounds of cargo they had just helped load?  It does include 3230 pounds for passenger weight.  An average of 170 pounds per passenger.  Company policy calls for adult passenger weight to be assumed at 160 pounds in the summer and 165 pounds in the winter for calculations, unless “weight obviously does not conform.”  They added a little weight, but the last time the average U.S. adult male weighed near 165 pounds was 1962.  The CG was calculated to be 0.4 inches forward of the aft limit.  Both the flight log and manifest contain math errors. Calculator anyone?

Let’s back up.  The director of operations was dismissed in February due to poor and inadequate record keeping.  This was about 6 months after accusations to the FAA of management pressure to fly overweight aircraft, although the former director reported he personally investigated employee accusations of improper weight and balance determinations during his tenure.  The new director and a new chief pilot rewrote the operations and policy manual and instituted more stringent weight and balance procedures.  One would think everyone involved in flight operations would be trained and clear on the recently updated policies and procedures.

The takeoff run is unusually long and the aircraft settles back to the runway on an initial attempt to lift off.  A second try is made after gaining more speed.  The climb out is noticeably steeper than usual.

As fuel is burned during cruise flight, the CG moves steadily aft.  Flight tests conducted with a specially configured Be 1900 were conducted up to 7 inches aft of CG, but not further for safety reasons.  This CG position resulted in neutral stability (where the aircraft neither tries to correct its attitude or deviate further after being disrupted) with flaps up.  With 20 degrees of flaps, neutral stability is reached at 3.5 inches aft of the published limit.

The Be 1900 rocks back and forth on short final, drops steeply, and impacts in a flat attitude at Homer, Alaska.  It slides in an upright position following impact.

Post crash calculations to determine the best and worst case center of gravity conditions were conducted.  Actual cargo weight was estimated to be approximately 600 pound over the FO’s request with 1600 to 1800 pounds in the aft baggage compartment.  Actual average passenger weight was 191 pounds.  These calculations estimated the Be 1900 was 400 to 500 pounds over maximum takeoff weight and 70 to 185 pounds over maximum landing weight.  During the course of the flight, the center of gravity was estimated to be between 8.43 and 11.2 inches aft of the limit of 299.9.  So the flight crew didn’t notice the aircraft was trying to depart controlled flight from the time they took off and getting progressively worse?  

Ryan Air Flight 103 crashed November 27, 1987.  The two pilots, who both helped load the cargo, and 16 of their 19 passengers perished.  The captain was one of three pilots involved in the accusation of management pressure.

Yes, weight and balance really is that important.  How do you ensure you’re not overweight or outside the CG limits?

Other safety issues discussed in Aircraft Accident Report NTSB/AAR-88/11:

  • Performance of the Beech 1900C
  • FAA oversight of Ryan Air
  • Ryan’s operations management

keywords: weight and balance, center of gravity, Ryan Air, AAR-88/11