13 Feb Basic VFR Dead Reckoning Flight Navigation
These short videos were created using X-Plane 11 to show an example of Basic VFR Dead Reckoning Flight Navigation.
When watching these videos, please keep in mind I do not follow the correct local procedures for the Northern Virginia area. This entire area is surrounded by the Washington DC ADIZ, so it is important to consult your flight instructor for the correct ADIZ procedures. The videos are strictly about the art of navigating using the skill of Dead Reckoning.
Navigating using the skill known as Dead Reckoning is really an art form, strictly using visual reference to the ground. Based on my experience, I actually believe it is harder than IFR navigation. Dead Reckoning is not as precise as using a GPS for navigating, but it is most certainly accurate enough to get you to your destination.
The most limiting factor about dead reckoning is that you need to make reference to the ground. That automatically rules out IMC days, so it is strictly only used under VFR conditions. Also, navigating across vast oceans like the Pacific without any reference to fixed ground references is not possible. They are the main limitations to dead reckoning that come to mind.
To carry out proper dead reckoning navigation skills, all you need is a watch, map and a compass. Remember Dead Reckoning makes no reference to any electronic navigation aids, such as VORs, VORTAC, NDBs, ILS, DME, LORAN or even GPS. As a pilot, you need to be able to accurately hold your selected heading and altitude for the duration. This is important for navigating accuracy.
The process is quite simple once you wrap your head around it. There is a simple formula I learned back in high school physics class. Velocity = Distance / Time. Using this formula, you need to know two components to calculate your answer. We need to know the distance and time to calculate the velocity. The formula can also be rearranged. Either way, we need to know two components of the formula to calculate the third.
Let’s just say we know where we want to fly. We use our visual navigation charts to determine the distance and magnetic direction to our intended destination. Okay, distance is one of the answers to the velocity formula. The magnetic direction is needed to know which direction to point the aircraft once we are airborne.
The velocity or True Airspeed (TAS) is determined based on our intended cruising altitude and engine settings. To determine the intended velocity based on specific engine settings, the pilot needs to make reference to the aircraft flight manual performance charts. The performance charts will determine the aircraft True Airspeed (TAS) for specific cruise engine settings. The TAS is the speed the aircraft will fly through the air in nil wind conditions. The performance charts also provide other vital information, the fuel flow for the selected engine settings.
Okay now we know what distance and speed we will be flying, therefore we can calculate the time it will take to get to our destination. If we rearrange the formula, we can calculate the Time it will take to get to our destination. Time = Distance / Velocity.
The fuel flow for our per-determined cruise engine setting will tell as the rate at which we will be burning fuel inflight. As a pilot, we need to know how much fuel we have onboard when we depart. Since we know how much fuel we will have onboard at departure and at what rate the fuel will burn, we can determine how long we can fly before we run out of fuel.
A pilot must ask this question during the planning process. Is the calculated flight time to my destination longer or shorter than the fuel endurance? This will enable you to determine if you need to stop for fuel on the way to your destination or not.
Now we have all the answers for our basic navigation flight; the heading, distance, velocity and time it will take to reach the destination. (In this case, assume we have enough fuel endurance that exceeds the calculated time to reach our destination.) With our calculated answers; if we point the aircraft in the correct direction, at the planned altitude and engine settings and note the time we depart, we can calculate the time we will be overhead our destination. It is quite easy and you will be surprised how accurate you can get.
In this simple scenario, I did not take the forecast winds aloft into account, which will effect the time it takes to reach our destination. The winds can work either in your favor or against you. Either way, in real life the winds are also taken into account. In both videos, I had the wind set to nil wind, to keep the exercise as simple as possible. With or without winds, the principles are the same. The winds will effect the time it takes to reach your destination and your heading that needs to be held in cruise. Fuel endurance is not effected by wind. Fuel endurance is determined by engine settings, which determines the fuel flow rate.
I hope you have found this article useful. If you have any questions, please feel free to send me an e-mail, reach me through one of various social media platforms or leave a comment below. Thank you.