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Map Centering and Range Rings

For Part 121 and Part 135 operators, our Bluetooth GPS receivers have been successfully tested, approved, and deployed under FAA AC120-76C for own-ship AMM display during taxi operations. At this time, the FAA does not allow own-ship display on portable devices while en-route. However, pilots can obtain most of the situational awareness improvements available through map-centering or range rings. These approaches, supported by some app vendors, assist in making the relevant portions of the map visible to the pilot's approximate position, thereby precluding the need for the pilot to scroll the map manually to find identifiable landmarks.

With map-centering, the app does not draw any indication of where the aircraft might be relative to the map.  It does scroll the map to show the general area in which the aircraft would be if the position were actually drawn.  By leaving the position of the aircraft off the map, the expectation is that the pilot will not be tempted to use the EFB display for primary navigation.

With a range rings  the app draws a circle of known range as its radius to highlight the general area of the aircraft on the EFB map.  This approach provides some additional context that can aid the pilot in more quickly identifying map contents for reference.

Some research has shown that either of these approaches can reduce the pilot's map search time by an order of magnitude, reducing a twenty second reference check to a two second reference check. The benefits have been significant enough that several major foreign airlines have encouraged AMM in all phases of flight and have operated hundreds of thousands of flight hours with improved situational awareness.

Own-ship Position and Aircraft Moving Map

Aircraft that operate under Part 91 (excluding Part 91F and Part 91K) require no EFB authorizations or compliance with AC120-76C, so long as the operator does not replace any equipment or operating information required by the regulations.  In other words, deploying an EFB to augment current operational policies is allowed, so long as the EFB meets the essential Portable Electronic Device (PED) regulatory compliance guidelines.

The Best GPS Accessory for EFB 

Commercial, corporate, military, and private pilots all over the globe use Bad Elf GPS receivers to augment their EFB to provide own-ship position, range rings, or map centering on the ground and in the air. Initially adopted by private pilots for early iPad models that lacked an internal GPS, Bad Elf GPS receivers found favor with pilots flying internationally. Bad Elf interviewed dozens of professional pilots to identify the most important features for an external GPS receiver.


The most essential capability must be to provide sufficiently accurate position information at normal operational speeds and altitude.  Bad Elf's GPS Pro and GPS Pro+ both operate up to 1,000 mph and 60,000 feet.  We've even heard rumors that some pilots have succeeded in flight faster and higher, but not both at the same time.


The most important differentiator for commercial and military pilots was knowing that the Bad Elf GPS receiver would operate all day long on a single charge.  For pilots flying long haul intercontinental flights, such as DFW to HKG, the flight alone exceeds 16 hours.


For the professional pilot on the road, lightening the load makes a difference. Bad Elf's GPS receivers weigh in at just over 3 ounces.  Compact and lightweight, they travel easily anywhere.


Combining great performance and features is all well and good, but it gets better when the price is right.  Bad Elf's receivers offer great value for the professional pilot. That value improves significant, because Bad Elf offers special discount pricing to professional and military pilots.

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