Not Complaining, Just Saying

So, I have a frustration to complain about..  These days I am flying our "Econ 2018" flights, trying to make money for my struggling little airline, Alak Air, flying "regional flights" out of the Minneapolis Hub.  You might wonder why I called it Alak Air.  I think the name is of Inuit origin, and it began when I was flying regional flights out of the Anchorage Hub.  It was the name from the livery my favorite Aerosoft DHC-6 Twin Otter, the one with the big tundra tires that work on cement, asphalt, grass or gravel runways.  One size fits all.  So, when i moved south to Minneapolis, I took the name with me, even though I'm no longer flying bush flights.
Since I am,along with our President /Webmaster John Rogers, a coauthor of the Econ 2018  "feature" here at SPA. I know how to maximize the profit margin on my flights.- find the smallest aircraft that can fit the specified passenger and cargo load for a given flight.  This means filling every, or almost every, available seat while still having enough carrying capacity to accommodate the assigned cargo.  If you've flown commercial recently, `you know this is how real world airlines work too - that's why even the middle seats are always full.
Sounds simple, right?  However, if you have been using Navigraph's great flight planning tool, Simbrief,(and you should be) you may have noticed their "Performance and Tools" feature.  It's a relatively new feature and it allows you to do the takeoff and landing analysis necessary to determine if you can safely take off or land on a given runway, dependent on your aircraft type and capability, the load you're carrying and the current weather (temperature, wind direction and speed, etc.).  Of course, you can't do this analysis until you have completed your flight planning and determined your fuel load, etc.  That job takes awhile, so you have to invest some time to know whether you should bid on a given flight in the list of offerings.  OK, no big deal, right?
So, here comes the complaint.  Of the last ten flights I have planned in the last month or so, I couldn't legally fly about 70% of them.  The usual reason is that I was over the maximum takeoff weight for that runway under the current conditions.  This number is less, often much less, than the nominal  maximum takeoff weight (MTOW) for the particular aircraft.  Why?  Well, it may be that the longest available runway is too short for your aircraft's required takeoff roll.  That might be just because it's a short runway, or because the longer runway is not oriented sufficient into the wind, or because the altitude, ambient temperature and/or humidity are too high to generate sufficient lift at the maximum airspeed you can achieve by Vr, while leaving sufficient braking distance to stop you before you overrun the runway.  That's because all three of these factors: increasing altitude, temperature and humidity,reduce the density of the air and with it the lift generated by a given wing at a given airspeed.  So a takeoff at a high altitude (Denver, Albuquerque, Jackson Hole) on a hot summer day are going to take a lot of runway.  So, this being August,, and since Cat III and IV flights from Minneapolis often go to/come from .the mountain west,, I've done a lot of planning this month for flights I couldn't/shouldn't fl;y.  I have also planned several flight from Minneapolis that terminated at a airport with short runways, where the landing analysis indicated that you could not safely land.  Today, I discovered a new prohibition: planning a flight from Albuquerque back to Minneapolis, I discovered that even their 13,793 ft. long Rwy 8 was too short because of rate of climb/terrain clearance.  My fully loaded CRJ1000 could not gain sufficient airspeed, sufficiently quickly to get over the mountains immediately east of KABQ..  Darn, foiled again!
Would these constraints actually prevent you from taking off/landing your aircraft in the simulator.  I'm not sure, I suppose that's a question of the fidelity of the simulator..  However, I will admit to having flown some flights in which I was rotating in the last few hundred feet of the runway.  While I got away with this, it would have probably cost me my job in the real world.  That's because V1 and Vr are usually pretty close together, which means that you didn't reach V1 until you were so close to the end of the runway, that, had you had to abort at V1, you would have been unable to stop before the end of the runway.

Always more than you wanted to know.

Mike