Narrative:

I took over this flight from morning dispatcher while the aircraft was out of service due to return to field with landing gear issue. We decided to delay the flight out until maintenance announces aircraft is airworthy for our scheduled flight. After a few tests from maintenance; they were unable to fix the problem; requested us route the aircraft to ZZZ in order to fix it and we complied. We canceled the scheduled flight and rescheduled the aircraft to go directly to ZZZ as a maintenance ferry. I started to flight planning after the decision of ferry has been made. In the process; I found out that E145 LR2 performance was not available and I could not continue my flight plan without it. So I stopped and asked coordinator for extra assistance. He notified dispatch manager and operations system support and we delayed the flight out furthermore. Few hours after; we were finally able to get E145 LR2 gear down performance data loaded into our data system with limitation of flying at 8000 ft. I observed and followed the airplane manual for flight with landing gear down to ensure the flight may be operated safely. I sent the release over and coordinator faxed flight with landing gear down supplement to station after all operation limitations were met. The captain and I discussed about the limitations and weather conditions over the phone and we both agreed it is safe to conduct the plan. The flight finally departed msy heading ZZZ. I received a radio call not long after they passed mei (meridian VORTAC) from the crew stating they have a higher fuel burn than planned. The crew advised me they are using more fuel than planned and their burn rate is about 4;000 pounds per hour with fuel on board of 7;400 pounds. I advised the crew to stand by and I will work on the fuel numbers for them again. I calculated from vxv (volunteer VORTAC) to ZZZ with the route planned will take about 3;000 pounds of fuel. On top of that I need to add the reserve fuel which makes our minimum fuel at 4;900 pounds from vxv (about 320 NM away). After that calculation; I started to look for alternate airports nearby just in case we won't have enough fuel when cross vxv. Weather was good all around the country that night. I found tys; sdf; gsp; atl; bna; are all reporting and forecasting VFR weather suitable for listing as alternate. The crew called again to check on the progress and alternate plan. They were informed about the plan of the possibility of diverting to alternate. When I asked them about their current fuel on board they told me 5;500 pounds. I looked on the flight explore and measured vxv is still about 150 NM away. At speed of 250 KIAS with distance 150 NM; I came to realize; we don't have enough fuel to continue to ZZZ. So I advised the crew to divert to bna and they did. Comparing the actual burn number and the planned burn number; our actual fuel usage was about 1;000 pounds more than planned when the crew first called me and at the second radio call our actual fuel usage was about 1;300 pounds more than planned. The plan I provided to crew had a very low accuracy on fuel planning. We ended up short on fuel and had to divert. Have a step by step training manual for gear down ferry like we had for medical emergency on all type and variations. Have a second person check the performance data we received.

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Original NASA ASRS Text

Title: Flight planning data for a gear down ferry flight of an E145 provided inaccurate fuel burn numbers and the flight must divert due to insufficient fuel.

Narrative: I took over this flight from morning Dispatcher while the aircraft was out of service due to return to field with landing gear issue. We decided to delay the flight out until maintenance announces aircraft is airworthy for our scheduled flight. After a few tests from maintenance; they were unable to fix the problem; requested us route the aircraft to ZZZ in order to fix it and we complied. We canceled the scheduled flight and rescheduled the aircraft to go directly to ZZZ as a maintenance ferry. I started to flight planning after the decision of ferry has been made. In the process; I found out that E145 LR2 performance was not available and I could not continue my flight plan without it. So I stopped and asked Coordinator for extra assistance. He notified Dispatch manager and operations system support and we delayed the flight out furthermore. Few hours after; we were finally able to get E145 LR2 gear down performance data loaded into our data system with limitation of flying at 8000 FT. I observed and followed the Airplane manual for flight with landing gear down to ensure the flight may be operated safely. I sent the release over and Coordinator faxed flight with landing gear down supplement to station after all operation limitations were met. The Captain and I discussed about the limitations and weather conditions over the phone and we both agreed it is safe to conduct the plan. The flight finally departed MSY heading ZZZ. I received a radio call not long after they passed MEI (Meridian VORTAC) from the crew stating they have a higher fuel burn than planned. The crew advised me they are using more fuel than planned and their burn rate is about 4;000 LBS per hour with fuel on board of 7;400 LBS. I advised the crew to stand by and I will work on the fuel numbers for them again. I calculated from VXV (Volunteer VORTAC) to ZZZ with the route planned will take about 3;000 LBS of fuel. On top of that I need to add the reserve fuel which makes our minimum fuel at 4;900 LBS from VXV (about 320 NM away). After that calculation; I started to look for alternate airports nearby just in case we won't have enough fuel when cross VXV. Weather was good all around the country that night. I found TYS; SDF; GSP; ATL; BNA; are all reporting and forecasting VFR weather suitable for listing as alternate. The crew called again to check on the progress and alternate plan. They were informed about the plan of the possibility of diverting to alternate. When I asked them about their current fuel on board they told me 5;500 LBS. I looked on the flight explore and measured VXV is still about 150 NM away. At speed of 250 KIAS with distance 150 NM; I came to realize; we don't have enough fuel to continue to ZZZ. So I advised the crew to divert to BNA and they did. Comparing the actual burn number and the planned burn number; our actual fuel usage was about 1;000 LBS more than planned when the crew first called me and at the second radio call our actual fuel usage was about 1;300 LBS more than planned. The plan I provided to crew had a very low accuracy on fuel planning. We ended up short on fuel and had to divert. Have a step by step training manual for gear down ferry like we had for medical emergency on all type and variations. Have a second person check the performance data we received.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.