Reprint: Aviation Refuel Planning Considerations

By Lt. Col. Gregory Sterley, Maj. Andrew Keithley, Capt. Joseph Keegan, and Capt. Ian Greer

Article published on: September 22, 2025 in the Fall 2025 edition of the Aviation Digest

Read Time: < 11 mins

This reprinted article was originally published in the Army Sustainment Professional Bulletin's Fall 2024 issue and is used with permission.

According to Joint Publication 3-18, Joint Forcible Entry Operations, air assault operations are a “movement of friendly assault forces ... to engage and destroy enemy forces or to seize and hold key terrain.” The maneuver allows ground commanders to mass combat power at critical points on the battlefield, creating multiple dilemmas for the enemy to slow their decision-making and their placement of ground units at a position of relative advantage. The air assault provides enormous amounts of combat power for the ground commander, but the precision that air assault operations require makes them inherently fragile. Any number of contingencies en route to the objective could jeopardize the operation. As a result, air assaults require thorough mission planning to ensure they achieve the effects that ground commanders desire.

With the Army’s emphasis on counterinsurgency operations over the past 20 years, air assault operations have largely remained at the battalion level and below. However, recent modifications and changes in operational thinking, as captured in top-level doctrine such as Field Manual 3-0, Operations, necessitate the resurrection of the air assault as a joint forcible entry (JFE) capability for the Army.

The 101st Airborne Division drives the charge with newly approved force design updates that bring a heavy-lift battalion. This allows the division a brigade-level JFE capability, which it lost with the deactivation of the division’s second combat aviation brigade (CAB), the 159th CAB. Recently the division conducted a series of long-range, large-scale air assaults (L2A2s) to overcome a two-decade gap in organizational knowledge about division-level rotary-wing JFE capabilities.

Refueling operations, too, have grown with the appetite for L2A2s and continuously prove a point of friction. Forward arming and refueling points (FARPs) require the same level of deliberate analysis and planning to prevent backlogs or stoppages to aviation operations. The most consequential factors limiting FARP operations during L2A2s are insufficient total capacity, insufficient unit capacity, the number of available refueling points, fuel flow, crew duty day, and FARP certification. While the 101st CAB continues to develop tactics, techniques, and procedures to overcome each limiting factor, commanders and planners must understand the risks of their implementation to identify appropriate situations for using them.

Total capacity is the simplest limiting factor to overcome. Adding more fuel-carrying vessels to a FARP site increases the amount of fuel on hand, and not all vessels need to be capable of refueling aircraft if fuel transfer is possible. Adding more M978 Heavy Expanded Mobility Tactical Truck (HEMTT) fuelers is the preferred method of increasing total capacity at a FARP location, due to their ability to transfer fuel to aircraft. However, the HEMMT has a relatively low capacity, and a fleet of them is not always sufficient for meeting total capacity needs.

Additionally, the lower capacity of the HEMTT and tank rack modules (TRMs) relative to the M969 fuel tanker or bulk-fuel carriers means that more of them are needed to meet the same total fuel capacity as that of M969 tankers and bulk-fuel tankers. This increases the total footprint of the FARP site and makes the sustainment node a larger, more obvious target for enemy forces. Adding bulk vessels, therefore, helps meet total capacity and aircraft requirements while largely reducing the FARP footprint. However, these bulk assets are limited in their operations on the fuel line if they lack an internal pump, and therefore are used to refill M978s with the associated HEMTT Tanker Aviation Refueling System (HTARS) attachment.

With the addition of HEMTTs or other bulk Class III-carrying vessels, planners must conduct more thorough analysis to determine a support package that facilitates the sequence and timing of aircraft serials (groupings) in the mission. To perform this calculus, logisticians must consider unit capacity, or the amount of fuel available to aircraft at a mainline. An implicit assumption in planning for total fuel requirements at a FARP site is that all fuel, regardless of the vessel that contains it, will become usable to an aircraft at some point in the mission. While obvious on the surface, battalion- and brigade-sized support elements must turn this assumption into a fact before mission execution to prevent serious backlogs or even mission stoppage en route to the objective.

Currently, the M978, M969, and TRM stand as the most proliferated and commonly used fuel vessels in the logistics community. However, only the M978 is widely available and capable of transferring fuel into an aircraft with the HTARS. This equipment is commonly found on a distribution or forward support company’s modified table of organization and equipment. The Forward Area Refueling Equipment and its variants continue to be an option as well, but its capacity (500-gallon collapsible drums) becomes a planning concern for L2A2 operations.

Support units have several options to overcome unit-capacity limitations, but the two most common techniques are (1) connecting multiple M978s to the same mainline and (2) increasing the number of mainlines above what the largest aircraft serial requires. Either technique, however, brings its own disadvantages. If support elements connect multiple M978s to the same mainline hose, fuelers gain the ability to transfer fuel from bulk vessels into one of the mainline vessels while the other mainline vessel distributes fuel to aircraft. This option, however, generally limits the number of aircraft in each serial because it also limits the number of mainlines available at a FARP. Additionally, support units risk more fuel becoming non-transferrable if anything damages or destroys the main fuel line or any of its valves.

Support units that increase the number of mainlines above what the largest aircraft serial requires gain the flexibility to move aircraft across different mainlines to effectively plan and schedule fuel transfer from bulk vessels to vessels connected to a mainline. This enables continuous fuel transfer to non-active mainlines. It also affords flexibility to the task force commander because it ensures the FARP can accommodate all aircraft in each serial, even if a dispensing vessel or main fuel line becomes inoperative. The support unit does assume risk, however, because as the FARP footprint grows with the addition of mainlines, this makes command and control over the total area more difficult and increases the logistical footprint.

The number of total points (fuel-distributing hoses) on a FARP is the most micro-level analysis planners must undertake to identify support requirements in aviation operations. To ensure all chalks in a serial (platoon-sized units) of aircraft receive fuel without spending time in holding, the number of points must, at a minimum, match the number of chalks in the largest serial. To meet this demand, support units again have two primary techniques: adding more hoses to the same mainline or adding more mainlines with the same number of fuel-distributing hoses. The technique the support unit uses to overcome unit capacity will drive which technique is more suitable to address the number of points.

For elements that increase unit capacity to a mainline by coupling vessels to a single line, adding more points to the mainline decreases fuel flow as the distance from the vessel increases. In cases of heavy-lift aircraft such as the CH-47 Chinook, fuel flow limits the number of feasible points to two per vessel. In the case of the AH-64 Apache or the UH-60 Black Hawk, four points are generally the maximum. Units that face limitations with this technique should consider adding more vessels to their FARP configuration to maximize flow and throughput, matching the number of fuel-distributing hoses (points) to the largest serial.

For elements that add more mainlines with the same number of points, the greater quantity of mainlines enables throughput via an increased flow rate to a lower number of points from each vessel. Adding more mainlines is a technique that benefits elements who need to decrease aircraft time on the FARP due to mission requirements. Though this technique increases the dependence on logistical infrastructure due to an increased reliance on maintenance of ground equipment, it renders the failure of a single point less impactful to the overall refueling plan. Since both techniques pose risks, the planning process necessitates constant dialogue between platoon, company, battalion, and aviation/sustainment planners to address mitigation techniques.

An additional limitation when setting refuel requirements during aviation operations is total flight time for pilots. Army Regulation 95-1, Flight Regulations, requires units to maintain a crew endurance policy. While the policy is unit dependent, common practice is to limit aircrews to 14 hours per duty day while performing flight-related duties, and to 6 to 8 hours of flight time without an extension, which generally requires O-6 approval.

The precise nature of air assault operations implies inherent risk, and extensions to duty day or flight time introduce fatigue and further increase the risk to the mission and the force. To avoid this constraint, three iterations of L2A2s in the 101st Airborne Division used the cold fuel process, where aircraft stopped their main engines to receive fuel, and reduced their flight time. This afforded the crews an opportunity to rest mid-mission, and effectively increased their alertness during their infiltration into the final objective, the most critical and dangerous part of the air assault. Under these conditions, cold fuel requirements are still time sensitive, and throughput is still one of the largest planning considerations, with the composition of the serial spending the least time shut down and total capacity determining the number of trucks required to support the mission. Cold shutdowns also feed into operational planning because they allow multiple landing-zone landings nearly simultaneously.

The final limitation planners face in large-scale aviation operations is the FARP certifying official. Doctrinally, there is no regulatory requirement that outlines which individuals in an organization can certify a FARP. Army publications such as Army Techniques Publication 3-04.17, Techniques for Forward Arming and Refueling Points, recommend that the aviation safety officer (ASO) or a “commander’s designated representative” be the lawful certifying official. However, they frequently use qualifiers such as “should” and “may,” indicating the techniques are preferred and not mandatory. As a result, the 101st CAB petroleum standard operating procedure, which permits the battalion safety officer, the ASO, or any command pilot designated by the battalion commander to certify a FARP, stands as the only regulatory document that appoints certifying officials.

Issues arise when non-aviation units seek to certify a FARP. Even in the aviation support battalion, a battalion organic to the CAB with its own aviation maintenance company, pilots in command are hard to come by, and FARP certification can become a significant point of friction if the appropriate personnel are not present before operations. This issue only compounds for non-aviation units as they look to exercise aviation refueling operations, since the only pilots in command within a brigade combat team belong to the brigade aviation element (BAE), who throughout planning are more than likely involved in acting as the liaison for their respective elements. Within the division sustainment brigade, the level of difficulty to coordinate certification only grows because no BAE exists to help coordinate aviation support, let alone self-certify. Due to the lack of regulatory requirements, non-aviation units seeking to support aviation operations should, and legally can, develop their own procedures to train personnel organic to their organization to certify FARPs.

While total capacity is a non-negotiable factor for planners at the brigade level and above, support units and aviators have flexibility in determining what risk is acceptable during FARP operations. Increasing unit capacity and limiting the number of mainlines at a FARP site are best suited for operations that require continuous, manageable throughput, such as massing friendly forces and assets onto an objective following the initial air assault, during reconnaissance operations where maintaining enemy contact is critical, or during continuous attacks on the enemy. The somewhat smaller footprint increases survivability, which is a critical consideration since a FARP supporting each of these missions would be nearest the enemy.

Increasing the number of mainlines, on the other hand, allows for larger serials to sequence through the FARP without having to wait for fuel. Thus, this is more suitable for heavy-lift aircraft, where fuel flow becomes a limiting factor, or for initial assaults into an objective when the ground force must meet its minimum force to complete its initial actions on the objective.

Hybrid options exist for support commanders as well, such as adding mainlines with relatively low additional unit capacity to a FARP, with a separate high unit-capacity mainline to facilitate maximum destruction and phased attacks as they transition to continuous attacks. In general, however, adding more mainlines is preferable in permissive environments because it enables more flexibility to account for broken equipment. The large footprint of this configuration, though, makes it less ideal for non-permissive or forward activity.

As the Army transitions its focus from counterinsurgency back to large-scale combat operations, aviation operations will continue to grow to meet demands of the division as it becomes the new unit of action. Sustainment leaders must produce thorough, deliberate plans that minimize friction during refueling operations to synchronize sustainment and movement and maneuver warfighting functions. Sustainment planners in the CAB must be aware of refuel limitations, how they affect operations, solutions to these limitations, and the risks that leaders assume in implementing each one. Sustainment leaders at echelon must synchronize their efforts to understand and mitigate limitations of total capacity, unit capacity, the number of points, refueling fuel flow, pilot duty day, and FARP certification. Leaders in the CAB and ground force must acknowledge these limitations and be receptive to potential changes they could drive in the scheme of maneuver. Indeed, the transition to the division as the unit of action will entail a level of coordination not practiced for nearly two decades, but this level of coordination will become necessary as aviation operations continue to grow in scale.