System proposed to electronically designate drop points for firefighting aircraft


Multi-Link Drop Computer
Example of a proposed display from the Multi-Link Drop Computer system; still a work in progress. Canaan Avionics.

When a drop from an air tanker is needed on a large wildfire, the drop point is usually described to the pilot verbally over the radio, or a lead plane says follow me and then flies over the area identifying the target area either verbally, such as “drop here”, or releasing smoke to visually mark the drop area, or both. The verbal description can be imprecise, and the use of a lead plane requires that the aircraft be committed to that purpose when the air tanker is making the drop.

Matt Richardson, an Avionics Systems Engineer with Canaan Avionics LLC, has designed a system called Multi-Link Drop Computer that would electronically record and then transmit to air tanker pilots detailed information about the desired drop, including navigation data to the drop point, inbound radial, drop point, outbound radial, wind speed, and wind vector. When building line, multiple drop points could be recorded and transmitted to incoming air tankers which would each be assigned a drop point.

Besides the obvious benefit of giving pilots detailed navigation information to the drop point, another advantage we can see is for incidents where the Air Tactical Group Supervisor (ATGS) and the Lead Plane duties are combined and performed by two people in one aircraft, known as an Aerial Supervision Module (ASM). There are times when the Lead Plane needs to be 150 feet above the ground leading air tankers to their targets, but it is also helpful to be thousands of feet up, gathering the big picture for the ATGS. As long as the drop points are not frequently changing due to a rapidly spreading fire, several of them could be recorded and saved, allowing the ASM to go upstairs for a while, directing air traffic, observing the fire, and developing aviation tactics and strategies.

(UPDATE December 11, 2014: we posted three videos that demonstrate the system.)

Below are some excerpts from a white paper Mr. Richardson has developed.


Multi-Link Drop Computer
Single drop. Multi-Link Drop Computer. Canaan Avionics.

“…Mission Example for LRN via Electronic Display: A Lead Plane identifies a fire ‘hotspot’ by flying over it and marking it with the MLDC. When the pilot presses the ‘MARK’ button, the MLDC instantly records the latitude, longitude, time, wind speed and wind vector at the drop point as received through the GPS data buss. If the pilot holds down the mark button, the MLDC will also record a desired drop length for the duration of the button press and aircraft track while the button is held will become the desired drop vector. The drop point data is given a unique waypoint identifier (FOX12 for example) and stored into a preset. The Lead Plane pilot can go into the MLDC menus and manually augment any of the drop point parameters if desired.

The Lead Plane sends the drop point, FOX12 through a TCP/IP connection by selecting an aerial assent in a list of preprogrammed tail numbers. The drop point data is sent through the onboard AFF Iridium connection to a C-130 still enroute and to a ground based mission coordinator.

The C-130 pilot receives the drop coordinates like an email in the cockpit and loads it into a preset. The C- 130 pilot radios the Lead Plane and aurally confirms that ‘FOX12” was received. The wind data attached to the drop point indicates that there is a heavy crosswind from the west so the pilot uses the MLDC menus to move the drop point 100’ due west.

The C-130 pilot selects the MLDC as the active NAV source using the EFIS controller and a flight plan is shown on the Multi-Function Display (MFD) from his present position to the FOX12 drop point. The drop point flight plan has an intercept vector that matches the drop vector attached to the waypoint. The pilot then selects ‘NAV’ on the flight guidance panel and the autopilot guides the aircraft towards the drop point. While flying to the drop point, the pilot monitors the flight plan and ensures that the predicted path of the aircraft does not impede with other aircraft or terrain. All data is displayed to the pilot on the existing MFD display.

Once the drop point is reached the MLDC sets a discrete which illuminates a ‘DROP’ annunciator to signal the beginning of the drop. The C-130 pilot initiates the drop sequence at that time. The MLDC extinguishes the annunciator once the drop length is reached and the C-130 ends the drop cycle. The MLDC monitors the drop sequence via discrete inputs and records the drop position, vector and length as received through the digital GPS buss.

The C-130 pilot confirms the drop aurally and sends an electronic drop confirmation to either the lead pilot and/or to the mission coordinator using the MLDC…”

MLDC line building
Line building. Multi-Link Drop Computer. Canaan Avionics.

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25 thoughts on “System proposed to electronically designate drop points for firefighting aircraft”

  1. So how do you determine altimeter setting, target elevation, coverage level required and exit information if a sharp turn is required immediately after the drop? When you say “a lead plane says follow me and then flies over the area identifying the target area either verbally, such as “drop here”, or releasing smoke to visually mark the drop area, or both” makes it sound like that is all a lead planes ffunction is.
    It minimalises the importance of critical information that the air tanker pilot relies on from the lead plane. Information that a machine can never duplicate i real time. Thanks but no thanks.

    1. JEB, some of your questions are answered in the white paper, regarding target elevation and the outbound radial. I would imagine that the system could also accommodate an input for coverage level. But you’re right, in that some information that is normally evaluated and shared in real time by the lead plane might be missing, such as visibility, turbulence, or winds created by the fire.

      There are many features of the system that I didn’t include in the short article above. If you’re really interested, or desire to form an opinion of the system pro or con, you should read the white paper.

  2. Between this and tcas a pilots head will always be down. There are times where having ones eyes outside may be the difference between becoming part of the fire or returning for a reload!

  3. Many Thanks to Bill for posting this. I will make myself available for any questions folks have. The intent of this system is to provide IFR flight guidance to drop points and a look-ahead terrain avoidance scheme which will prevent CFIT.

    Those fighting fires are doing an incredible job, and you guys arguably have one of the most demanding piloting missions there is. In my studies of flight operations, I noticed that pilot workload for drop operations is very intensive. Most pilot workload is dedicated to navigation; especially in regards to the amount of radio communication. With the help of a flight director and IFR guidance, the MLDC will drastically reduce pilot workload while actually increasing the time that a pilot can spend ‘heads-up’. This was a key finding from the original NASA evaluations of NextGen VLAT’s and to date this finding has been unresolved.

    I have the MLDC integrated in a high fidelity simulation. The MLDC is so accurate that the target can be acquired beyond 30nm, which is standard for all terminal procedures. Empirically derived drop data from grid tests, along with real time wind data, allow the drop navigation to be compensated for wind conditions and variations in drop altitude. In the fight simulator I’ve even done drops at night with the exact systems safety requirement limitations defined in AC 25.1309. I am currently updating the system to provide wind-shear warnings. In total, the MLDC will save lives while making drop operations more efficient and more accurate.

    1. Matt,

      Take a look at FAA 8260.52 requirements for LPV approach certification for airports. I think the hard part of your concept is going to be approval of terrain survey capability to support drops at or below 200′ AGL. Obstacle clearance evaluation is pretty complex.

      On the other hand, the UAS people would probably jump on your concept to support night ops.

  4. This application or parts of it could possibly include sending the drop info thru AFF so areas are mapped for environmental reporting requirements and assist with cost apportionment and recovery of funds for claims.

    1. Yes. The current AFF infrastructure could be leveraged. Experiments into the latency of telemetry data would have to be done. However, it’s been shown that using an on-board VHF Comm and packet radio protocols can yield real time telemetry with only a few seconds of latency. You guys fly with FM tactical radios. The MLDC will reduce radio traffic on those (by nearly eliminating conversation about navigation), while the modem uses a VHF com on an unused channel.

      1. Whatever develops from your efforts are worthy of consideration. There is always downsides to any new developments. More radios, IPads and have surely taken eyes from the tasks at hand. There is an art to good target description but we all know it can result in negatives too. The interchange of information between aircraft was studied years ago. It did not come to anything then but technology moves forward. Lets see what comes of it. I remember some folks gar mouthed type one helicopters when they first started. We’ll give me a crane and water (maybe some foam) on heavy fuels working with crews for taking care of business. Consider incorporating digital transmission of divert information to aircraft which I believe would reduce some painful to listen to narrative that pilots have to endure. Good luck to you.

        1. The MLDC definitely doesn’t fit all use cases, and I know what you mean when you mention technophobia. WAAS/LPV technology is the precedence for all this. NextGen VLATs change the paradigm significantly. VFR doesn’t work well when aircraft travel so fast and require longer stretches to trim out and establish glidepath. Its a testament to the tanker pilots and lead planes how well they’ve made it all work with just a puff of smoke and a radio. I’ve watched days worth of operation videos, and the airmanship is top notch.

          I’ve flown MLDC missions in the lab, and it really makes fire fighting boring. Straight in, straight out approaches from over the horizon. Established flight paths organize the traffic, reducing the need for TCAS. Go-Around Advisory and Windshear call-outs provide a CFIT safety net. Flight Guidance and a moving map give ultimate situational awareness. The pilot can keep his head out the window full-time, while the copilot may run the throttles, keep and eye on instruments, and be heads up the other 2/3 of the time. I imagine the drop operation could be as safe and routine as any Part 121 approach operation, if not more safe in some ways given that the pilot always goes-around.

  5. That might be right, Joel

    Take it from a G1000 operator who knows about heads in cockpit


    I am giving Matt a slight pass on this…I am half way through the White Paper

    With all that other “proposed technology” out there to include UAS and UAV non certificated operators, I am giving to guys who can a least refer to the FAA AC 25.1309 Advisory Circular. He has at least proved beyond a shadow of a doubt, that he can master FAA “stuff” where as the folks loving other technology and UAV are just beginning to spell it and trying to work within a system instead of bucking it..

    People lectured me back in the past about bucking the system in the LMA world… it is time to take a dose of of the medicine….

    Many of us already know the possible danger of too much heads down in cockpit……is the LMA world ready to PAY for this technology and or an HUD when the contracts start showing up or is the LMA world going to try getting by on the cheeeeeeeeeep if old Matt lights up his idea(s)????

  6. A very interesting concept, Matt, but it appears from the video examples that approaches are being considered into rising terrain. No right-minded agency will allow those in the SOPs. Murphy states that if things can go wrong, they will. The worst-case scenario is the airtanker suffering an engine failure or loss of power on approach, coupled with the inability to jettison the load. All runs onto final must be made at a level or descending profile, and consistent heights above terrain should be maintained in order to achieve the optimal coverage levels of the product on the ground. Have you considered the delays involved if airtankers have to roll up to a previous drop rather than tag onto it? These opposing-direction runs – often dictated by terrain or obstacles – might require localiser/glideslopes and go-around profiles conflicting with each other. It would be akin to conducting conventional IFR operations on both ends of a runway in short succession. Hmmm.

    1. Hi Chris. The issue of doing drops on an incline can be resolved by increasing altitude. The MLDC is strapped with aircraft specific climb performance data. The approach cannot be enabled unless the aircraft, assuming an engine out and full gross weight, is able climb out at any point in the approach profile while maintaining configured GAA warning and caution thresholds. The MLDC won’t let you do an unsafe approach, regardless of terrain. The MLDC also has a feature which reverses the course with a simple button press and gives you guidance to do the approach from the opposite direction if desired.

      I have considered having differing approach and go-around vectors leading into a drop. However, it is absolutely unsafe to be anything other than wings level anywhere near the ground. This dictates that the approach and departure be on the same radial for “some” time. That said, the MLDC can be programmed with simple procedures, much like a STAR and SID, providing feeder course fixes, RF legs, etc. I have a menu when enables the user to automatically add these fixes to any approach.

      1. Matt, the problem with simply increasing the altitude when facing rising terrain, is that the new height above terrain will affect the pattern of the retardant on the ground. The longer the product ‘hangs’ in the air, the more it will be affected by winds and convection, leading to a pattern that is too wide, or too light in coverage, or both. Having a predictable coverage level of the ground remains the sole objective of aircraft delivery. This increased hang time can’t be compensated by merely stepping left or right; as clever as the software may be when assessing local real-time winds and laterally offsetting the approach, it can’t yet react as accurately or as quickly as a skilled pilot using visual cues.

        It’s good the MLDC reverse course feature enables quick ‘n easy one-touch profile replanning, but the length of time for the aircraft to manoevre into place and commence that new approach will take much longer than if simply relying on a pilot to do the same thing visually. The concept of successful and efficient aerial firefighting relies upon quick processing of assets over the fire, particularly when dealing with short-term suppressant delivery.

        Please note I’m not discounting your proposal, I’m merely offering constructive criticism with certain features.

      2. I would caution you to not use absolutes in describing something you haven’t done. Turning drops are not that uncommon. I’ve flung a horseshoe shaped line of retardant out of a steep turn around a house as the fire rapidly approached it. Fire truck parked in the driveway to support the retardant line.

        I’m intrigued by your concept and look forward to learning more about it.

  7. I for one am all for new innovations, but aerial firefighting has been, is now and will pretty much a seat of the pants operation. You have to have a FEEL of what the aircraft is doing, or what it might do. it is deffinately not an approach to landing and a go around scenario. As shown early on with the VLAT’s

    I would have to see this work before I’d sign on. Way too many variables in this type of environment.

    1. In my talks with the forest service, some have actually been reluctant to use VLATs to their fullest potential because of all the “variables” associated with VFR operations. The first commercial jets required 4 crew members. C-130’s sometimes had 5 crew members, all of them very busy. A 747-400 only has two crew and that is because of avionics that reduced workload. Avionics is supposed to reduce the number of “variables”, allowing you to keep your attention on the fight envelop, the mission objectives, and how things “feel”.

      The fire traffic area is a very intensive navigation and coordination zone. The MLDC takes that job off your hands.

      1. Matt,

        Have you requested to fly along with Air Attack on initial attack and extended attack incidents to gather more data about how MLDC might work?

        1. Not yet. Most all I know comes from studying videos and talking to crews. I am going on a trip soon to talk to some folks about some ride-alongs. I need that experience.

  8. Mr. Richardson, one thing is that you are receiving is a lot of good feed back from folks in the “seat”. I would pay close attentions to their comments, I see some very good feedback. I think many tankers pilots on large fires would feel somewhat uncomfortable without a lead. The leads human feedback i.e. getting too smoky, winds are turbulent and rough lets, find another spot (to drop) I thought I saw a helicopter where we want to run the pass, are part of the “feel” component. Tanker flying is a stick and rudder business regardless of the size of the air tanker. Like I mentioned lots of good info from commenters. You mean there could be more to tanker flying other than keeping an eye of the oil temps and fiddling with the manifold pressure and r.p.m.s. Good Luck.

    1. Thanks Johnny,

      There’s a lot of experienced people in this thread, and I’m hoping to soak up as much as I can.

      The lead plane’s role, even in MLDC operations, is paramount. I’d like to see lead planes using an MLDC to fly the approach, then send the exacting NAV data back to a tanker. Then the lead plane would have more time to communicate the “feel” of the drop because they wouldn’t be trying to show the tanker where the drop actually is. There are many use cases.

      I am also hoping to find folks who are wanting to find new horizons, win contracts that don’t exist yet (like night drops). The MLDC provides CAT II guidance, with a go-around which is above any CAT II minima. Drops at night, directly on the fire from, say 800′ above, could help raise the humidity when the fire is weakest. I know this isn’t normally done, but in my talks with the Feds and others, there are people interested in this.

      Given that my biggest disadvantage is experience, I’m always humbled to know that fire aviators have a distinct experience that can’t be found anywhere else and I’m honored that this community is always willing to share it.

      1. I think you’re on the right track with having the Leadplane fly the route, record it, and transmit the route back to the tanker.

  9. Fifty years ago “you can’t spray crops at night. Technology (low tech) dispelled that myth, night lights, forward and turn. The pure beauty of long term retardant is that it does evaporate significantly upon release, especially after the sun goes down (not test data on this one). However drops made near evening cut off will usually stay “wet/effective” through the night. Forest Service in one of their numerous retardant/airtanker evaluations demonstrated retardant dropped from 500 agl treated the ground with effectiveness to retard, daylight test. So forget about rising the humidity (retardant does do that very well) go for 500 to 1000 foot drops at night.

  10. I should have proof read my comments better. Retardant DOES NOT evaporate, it dries out over time. Is that the same? Anyway, the possibility of delivering retardant at night has always been of interest to me. I remember on to many occasions (as most of the fire fighters with a few decades under their belts) that when the sun comes up (heating with a break in the inversion) that the fire was going to come out of the canyon and destroy whatever was in its path, many times homes. After thinking about the 500 to 1000 feet drop height above the fire that is probably too far out there. Test data DOES exist (F.S.) at altitudes up to 500 agl. With the next generation air tankers there should be no reason for technology not to “catch up” with the tankers.

    1. You’re right, the effectiveness of retardant is almost completely independent of whether it is wet or not. The videos of the USFS labs burning mats of wood shavings treated with retardant and left to dry out completely for months, then burned, compared to an untreated mat is just astonishing. It’s the chemicals, not the water.

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