Ifly 737- Max 8 - Fuel Deficit/Range exceeded warning

[ricardo404]

Hello, Simbrief team! I would like to share with you an issue related to the Ifly 737 Max and see if there is anything that can be done about it.

I have been using the Max on long flights, replicating some real routes flown with the 737 on these long routes. I chose a specific flight departing from MDPC (Punta Cana) to SAEZ (Buenos Aires). This flight is operated by Arajet in real life, under number DWI6260, and can be consulted on platforms such as Flightradar or FlightAware. When reproducing exactly the same route as the real flight, the total distance is 3,290 nautical miles. According to information from Boeing, the maximum range of the 737 Max is approximately 3,620 nautical miles. However, of course, this number does not take into account atmospheric factors and other effects that can impact the range, either positively or negatively.

The problem is that when trying to fly long distances following real routes, Simbrief always displays the following warning: “Warning: Flight exceeds aircraft range” accompanied by a fuel deficit alert.

Specifically in this case of the Arajet flight, I received a warning that the route exceeded the aircraft’s range. Even so, I decided to continue with the flight. After finishing it, I took a photo of the amount of fuel in the tanks for analysis, as we can see:

Print of the flight generated by Simbrief and the warning of exceeding the range for the aircraft:

Regarding the Profile, I used the one from Ifly itself, already included in Simbrief, without making any changes or creating a custom airframe.

My question is: since I’m flying close to the 737 Max’s range limit, is this warning about exceeding the range due to the aircraft’s own limit, or could it be related to the 737 Max’s performance data from Simbrief?

[SimBrief]

It is normal to sometimes get this warning when flying close to the aircraft’s limit. It just means you need to fine-tune your options.

The Boeing range is calculated under ideal conditions. The actual range can change day-by-day and depends on many factors, such as upper winds, air temperature, passengers/cargo, cost index, how far away your alternate is, how much extra/contingency fuel you require, etc. It is normal for the actual range to be slightly lower than what is advertised in Boeing marketing documents.

You simply need to do some manual tuning to make this flight possible. The fuel deficit is quite small so you likely only need to make a small change, for example:

• Planning less passengers (your OFP had planned 156, if you set 149 the flight becomes possible)
• Planning less contingency fuel (your OFP had set 5%, you could use a fixed value of 15 minutes instead)
• Choosing a different alternate airport (for example SUMU is closer and requires less fuel)

Having to fine-tune a flight plan when close to the maximum aircraft range is perfectly normal and not an indication of a bug.

Best regards,

[ricardo404]

Yeah, on the one hand you’re right, I never thought about changing the contingency fuel! It never crossed my mind to change it. I think I’m satisfied with the answer. Thanks, Derek.