Hi, I was hoping you guys could help me figure this out.

I was contemplating about adding a second fleet type to serve the sub 100 pax routes since the 737 only comes in a 120 seater. (I'm not taking used AC into account).

So I set out to do some route research and aircraft research to see if there was a viable option for my needs. The only smaller plane that I found a viable option to the 737, or as an addition was the BAC One-Eleven 475/500. I ruled out the Fokker 28 due to high fuel burn and no extended/short fuselage version.

When I'm sitting here and comparing the 737 200adv with the BAC One-Eleven series I can't get the numbers to add up.

Both AC types have the same number of pilots and crew.

Both AC types have the same turn-around times.

Both AC types have very similar cruise speeds.

The lease costs:

737-200Adv (Similar range as 1-11-500 Series) = 114.000 USD per month

One-Eleven 500 = 120.000 USD per month

One-Eleven 475 = 111.000 USD per month

Fuel burn:

737-200Adv (Similar range as 1-11-500 Series) = 3050 kg/hr

One-Eleven 500 = 2390 kg/hr

One-Eleven 475 = 2370 kg/hr

Is the extra fuel burn on the 737 enough to justify adding a second type to the fleet?

Or is it more economical to stick to the 737 fleet and fly on 70-100 pax routes with the 737?

Based on todays fuel price and a fleet of 10 AC with an 18 hour utilisation the weekly fuel difference is ROUGHLY 55.000 USD pr week or 5.500 pr plane. That doesn't seem like a lot and it is very unlikely I will get 18 hours of FU pr day due to the time it takes to turn the AC around for next flight.

Is my math completely and thinking way off and am I forgetting something very important here?