Why should I choose APG?
APG is the industry leader in Runway Analysis. We have been providing data to commercial and business aircraft operators for over 40 years. Our easy-to-use applications allow you to calculate your required Runway Analysis and Weight & Balance data anywhere, anytime. Our tailored Engine-Out Departure Procedures (EOPs) allow for a maximum allowable takeoff weight that is unparalleled in the industry. We also have relationships with many aircraft manufacturers, so we are able to provide services for your entire fleet, eliminating the need for multiple service providers.
On what devices will APG products work?
APG works on many popular Apple devices. As of May 2016, we support:
- iPad 2 and up (specifically, iPad 2, 3, Retina, Air, Air 2, Pro 9.7″, Pro 13″, Mini, Mini 2, Mini 3, and Mini 4)
- iPhone 4, 4s, 5, 5c, 5s, 6 and 6 Plus, 6s and 6s Plus, and iPhone Se
We suggest that you use Safari, Chrome, or Firefox browsers to run our web-based programs. Internet Explorer may also be used.
How frequently can I look forward to seeing new features?
We regularly upgrade our applications and add new features. Significant features are typically announced around the time of the large tradeshows, such as NBAA, EBACE, and ABACE. For information about our current product offerings, please visit us at the Apple App Store at https://itunes.apple.com/us/artist/aircraft-performance-group/id370256841.
How do you charge for your services?
Can I access APG anywhere in the world?
Yes, you can. APG‘s iPreFlight is a stand-alone application, so you can even access it while airborne without an Internet connection. This is especially important when you need to determine performance changes on the fly. APG‘s web-based products can also be accessed anywhere you have an Internet connection, regardless of country or continent.
How can APG help me achieve better takeoff and landing weights?
When a departure is determined to be obstacle-limited, APG will develop a custom Engine-Out Departure Procedure (EOP). These procedures are developed to increase maximum allowable takeoff weight while remaining safe and compliant. EOPs are developed by request and at no charge to the customer.
Which aircraft do you support?
APG currently supports over 200 aircraft types from manufacturers including the following:
- Bombardier Inc.
- British Aerospace (BAe)
- Canadair Ltd.
- Cessna Aircraft Company
- Construcciones Aeronáuticas SA (CASA)
- Dassault Aviation
- DeHavilland Aircraft Company Ltd.
- Dornier Flugzeugwerke
- Eclipse Aviation Corporation
- Embraer S.A.
- Fairchild Aerospace Corporation
- Gulfstream Aerospace
- Hawker Aircraft Ltd.
- Israel Aerospace Industries Ltd.
- LET Aircraft Industries
- Lockheed Corporation
- McDonnell Douglas
- Metro Aviation
- Mitsubishi Heavy Industries
- North American Sabreliner
- Piaggio Aerospace
- Raytheon Aircraft Company
- Saab Group
- Short Brothers Plc. (Shorts)
- Sukhoi Aviation Holding Company (JSC)
Will I be able to access my APG data at any time of the day or night?
APG‘s data is available 24 hours a day with very high service reliability. Data can be generated whenever you need it, wherever you need it.
What does APG provide?
APG delivers Runway Analysis and Weight & Balance information via our suite of iPhone, iPad, and web applications. Runway Analysis is a determination of maximum allowable takeoff and landing weight that accounts for the specific aircraft, weather, runway, obstacles, etc. for your unique case. Weight & Balance is the determination of the weight of the aircraft and whether that weight is within center of gravity limits (CG envelope).
What is runway analysis?
Runway Analysis is the resultant limit weight from a series of calculations used to determine the maximum takeoff and/or landing weight for a given aircraft. The calculations utilize the manufacturer’s approved Airplane Flight Manual (AFM) data in conjunction with a completed set of obstacle/terrain data and all runway characteristics, including declared distances. Takeoff weight calculations consider the following elements to determine the most limiting weight:
- Maximum Takeoff Weight (MTOW) – the maximum structural limit weight
- Climb Limit Weight – the maximum allowable weight for conditions at takeoff that will allow the aircraft to meet the aircraft certification minimum climb gradients for each of the takeoff segments
- Field Length Limit – the maximum allowable takeoff weight that will allow the aircraft to meet the aircraft certification rules governing the runway’s declared distances, slope, runway contaminants, airport elevation, and environmental conditions (wind, temperature, and pressure)
- Obstacle Limited Weight – the maximum allowable takeoff weight that will allow the aircraft to meet the regulatory authorities’ obstacle clearance requirements considering aircraft configuration, obstacle height/distance, and environmental conditions
- Brake Energy Limit – the maximum allowable weight at which the brakes can absorb the amount of energy (heat) required to stop the aircraft
- Tire Speed Limit – the maximum allowable weight at which the takeoff speed does not exceed the tire limit speed
Landing weight calculations consider the following elements to determine the most limiting weight:
- Maximum Landing Weight (MLW) – the maximum structural limit
- Climb Limit Weight – the maximum allowable weight for conditions at landing that will allow the aircraft to meet the aircraft certification minimum climb gradients in the approach and landing configurations for the airport elevation and temperature
- Field Length Limit – the maximum allowable landing weight that will allow the aircraft to meet the aircraft certification rules governing the runway’s landing distance available, slope, runway contaminants, airport elevation, and environmental conditions (wind, temperature and pressure)
NOTE: Complying with slope is not an FAA requirement and is used only for those aircraft having manufacturer’s slope information.
Do you have a charge for one-time use?
We charge on a monthly subscription basis only at this time.
How many airports does my subscription allow me to access?
All subscriptions give access to our worldwide database of over 8,550 airports.
How many users can have access?
The APG WB and iPreFlight apps require one-time use codes for login on the iPhone/iPad. We will issue up to four access codes per tail to access the account. Additional codes may be provided on a case-by-case basis. ATLAS and APG WB use one common login for each account.
Does APG monitor NOTAMs?
APG subscribes to NOTAMs via the FAA Aeronautical Information Data Access Portal (AIDAP). However, with over 8,550 airports within the APG database, it is simply not possible to monitor NOTAMs on a daily basis. We instead ask customers to contact us, either by phone or email, when a customer encounters a NOTAM that they believe may impact performance. We will then analyze whether the NOTAM will affect aircraft performance and will make the appropriate corrections. We also have the ability for users to interactively adjust runway lengths if they encounter a NOTAM closing a portion of the runway. This is the “Shorten Runway” tool and is available in all of our current product offerings.
Am I really only clearing obstacles by 35 ft.?
No, there is a safety margin built into AFM performance data. This safety margin is outlined in Part 25 (Aircraft Certification), but takes a conservative approach to the actual data gathered by the test pilots upon certification. The most common way to be conservative is by reducing the gross climb gradient to a net climb gradient factor. Reducing the climb gradient from gross to net creates a reduction in the aircraft’s actual climb performance as a function of the number of engines. The decrement ranges from 0.8% (for a two-engine aircraft) to 1% (for a four-engine aircraft) for first, second, and third segment climbs/acceleration. For an example, click HERE.
If you are clearing an obstacle by a net 35 ft. and the obstacle is 2 NM off of the departure end of the runway, you will actually be clearing that obstacle by at least 135 feet. At 10 NM, this becomes clearance of over 500 ft. To determine the actual aircraft height above the 35 foot net height, simply multiply the gradient reduction (such as .008) by the distance to the obstacle in feet. Please note that this assumes the worst-case scenario of losing the critical engine at V1, continuing the takeoff, operating at the maximum weight allowed for that scenario, and the obstacle in question being the most limiting obstacle. If the engine failure occurs after V1, or you depart with a lower weight than the maximum for that scenario, you will further increase this safety margin.
Is it possible to display the second segment climb gradient on APG's analyses?
APG does not currently display the second segment climb gradient. Providing this information to the end user promotes the practice of comparing the one-engine-inoperative second segment climb gradient to the TERPS/PANS-OPS all-engine minimum climb gradient required. This is not the intended means of meeting the FAR/EU-OPS obstacle clearance requirements and is a common misconception within the aviation industry. Please review the FAQ “Does APG’s data meet TERPS requirements?” for more clarification on the difference between TERPS and a proper Runway Analysis.
Does APG's data meet TERPS requirements?
This is probably the most frequently received question at APG. The short answer is that no, our data does not specifically take into account TERPS/PANS-OPS all-engine minimum climb gradients. A proper Runway Analysis using your Airplane Flight Manuals (AFM) One-Engine-Inoperative (OEI) performance data is required by the FARs and is a more accurate, detailed analysis for the specific aircraft and situation with which you are operating.
TERPS climb gradients are based on normal, all-engines-operating conditions; are not regulatory; and often ignore low, close-in obstacles. Comparing TERPS gradients against OEI climb performance in the AFM’s performance section (typically second segment climb data) is not an overly conservative method of determining obstacle clearance. OEI Runway Analyses do not always meet TERPS requirements, nor are they required to. TERPS, on the other hand, do not guarantee that OEI obstacle clearance is met; thus, following TERPS climb requirements may not meet the requirements set forth by the FARs. TERPS requirements are frequently set for noise abatement, ATC preference, navigational aide reception, etc.
Here is an excerpt from Advisory Circular 120-91 that explains the difference between TERPS climb gradients and an OEI Runway Analysis:
7. TERPS CRITERIA VERSUS ONE-ENGINE-INOPERATIVE REQUIREMENTS.
a. Standard Instrument Departures (SID) or Departure Procedures (DP) based on TERPS or ICAO Procedures for Air Navigation Services — Aircraft Operations (PANS-OPS) are based on normal (all engines operating) operations. Thus, one-engine-inoperative obstacle clearance requirements and the all-engines-operating TERPS requirements are independent, and one-engine-inoperative procedures do not need to meet TERPS requirements. Further, compliance with TERPS all-engines-operating climb gradient requirements does not necessarily assure that one-engine-inoperative obstacle clearance requirements are met. TERPS typically use specified all-engines-operating climb gradients to an altitude, rather than certificated one-engine-inoperative airplane performance. TERPS typically assume a climb gradient of 200 feet per nautical mile (NM) unless a greater gradient is specified. For the purposes of analyzing performance on procedures developed under TERPS or PANS-OPS, it is understood that any gradient requirement, specified or unspecified, will be treated as a plane which must not be penetrated from above until reaching the stated height, rather than as a gradient which must be exceeded at all points in the path. Operators must comply with 14 CFR requirements for the development of takeoff performance data and procedures. There are differences between TERPS and one-engine-inoperative criteria, including the lateral and vertical obstacle clearance requirements. An engine failure during takeoff is a non-normal condition, and therefore takes precedence over noise abatement, air traffic, SIDs, DPs, and other normal operating considerations.” READ MORE.
Now, here is the long answer: According to CFR Part 121.189 and CFR Part 135.379, “No person operating a turbine engine powered airplane may take off that airplane at a weight greater than that listed in the Airplane Flight Manual….” This means that anyone who is operating an aircraft under Part 121 or Part 135 must abide by the performance section of the Airplane Flight Manual (AFM). The performance section’s obstacle clearance requirements are governed by CFR Part 25 (Aircraft Certification) and are based on the worst-case scenario of losing the critical engine at V1.
For Part 91 operators, it is less clear whether or not a complete Runway Analysis is required. In short, Part 91 operators flying in IMC conditions must fly a procedure that ensures obstacle clearance for the aircraft they are operating. The only way to ensure this obstacle clearance is met is to use a complete One-Engine-Inoperative Runway Analysis.
14 CFR Part 135 outlines the obstacle clearance requirements that must be included in the AFM. Briefly, these require the aircraft to clear all obstacles by a net 35 ft. vertically or by 200-300 ft. horizontally, depending on whether or not the aircraft is within airport boundaries. In 2006, Advisory Circular 120-91 was published to set a new standard for the width of the corridor in which operators should be considering obstacles, as well as clarify some misconception regarding TERPS versus Runway Analysis. This new corridor is very similar to that found in Part 25, but it is slightly more conservative and allows for an aircraft to drift off of the intended flight path and still be within the corridor in which the obstacles were analyzed. This differs from TERPS because TERPS give a general corridor based on numerous criteria such as wingspan, normal operating speeds (i.e., accelerating to 250 kias below 10,000 feet), available navaids, terrain in the area, airport surveys, turning procedures, ATC, etc. TERPS are not based on an intended flight path for a specific aircraft and situation, but on a large area that can accommodate everything from a C172 to an A380. Because of this, TERPS will often require a steeper climb gradient than is needed to cover all possible intended tracks for the SID/ODP.
In the event of an engine failure, APG’s Runway Analysis assumes the pilot will maintain extended runway centerline track, or, if an APG-published Engine-Out Departure Procedure is used, APG assumes the pilot will follow that EOP as described in the textual page that accompanies any data on the EOP. This allows APG to meet all requirements set forth in the AFM for obstacle clearance while utilizing the corridor specified in AC 120-91.
As mentioned in AC 120-91, another downfall to TERPS is that there is a stipulation that allows for certain low, close-in obstacles to be ignored in the calculation of a TERPS climb gradient. A prime example of this is at Teterboro Airport (KTEB) in New Jersey. At the time of this writing, when departing the Teterboro Eight Departure, the TERPS climb gradient required is 500 ft. per NM, or about 8.2%. There is also a note that reads, “RWY 6: Sign, poles, buildings, and trees beginning 235 ft. from DER, 10 ft. LEFT of centerline, up to 106 ft. AGL.” Had these obstacles been considered in the creation of this SID, the minimum TERPS climb gradient required would be approximately 2,750 ft. per NM, or 45%. Obviously, this climb gradient would be impossible even with both engines operating, so the obstacles are removed from the analysis and added in text form on the SID. However, according to the CFRs and AC 120-91, you are required to clear all obstacles by a net 35 ft. within a corridor that is 200 ft. either side of centerline. Given that this obstacle is listed at only 10 ft. offset of extended centerline, it not only becomes a regulatory requirement but also a safety requirement.
At APG, we take these obstacles into account and determine whether they fall within the corridor outlined in AC 120-91. If they do, we analyze the performance in such a way that will allow the aircraft to clear all known obstacles by the required 35 ft. net. In this particular case, an aircraft will likely never reach a 45% climb gradient; weight is going to be reduced to a point at which the aircraft is able to complete the takeoff distance required prior to the end of the runway, thus giving the aircraft time to climb before the DER. This allows for a much lower minimum climb gradient required but still ensures obstacle clearance requirements are met.
For more information on the subject, the following NBAA article also gives a detailed explanation of the difference between TERPS and Runway Analysis:
How can I fly the APG Departure Procedure if I filed for — and have been cleared for— an ATC published SID/ODP?
This question is best addressed by referencing Advisory Circular 120-91:
An engine failure during takeoff is a non-normal condition, and therefore takes precedence over noise abatement, air traffic, SIDs, DPs, and other normal operating considerations.
b . In order for an operator to determine that a departure maintains the necessary obstacle clearance with an engine failure, the operator should consider that an engine failure may occur at any point on the departure flightpath.
The most common procedure to maximize takeoff weight when significant obstacles are present along the normal departure route is to use a special one-engine-inoperative departure routing in the event of an engine failure on takeoff. If there is a separate one-engine-inoperative departure route, then the obstacles along this track are used to determine the maximum allowable takeoff weight for that runway.
Consideration should be given to the possibility of an engine failure occurring after passing the point at which the one-engine-inoperative track diverges from the normal departure track. Judicious selection of this point would simplify the procedure and minimize the difficulty of this analysis. This is generally achieved by keeping the two tracks identical for as far as is practical.
In some cases, two or more special one-engine-inoperative tracks may be required to accommodate all the potential engine failure scenarios.
In general, when APG determines that a turning Departure Procedure is required due to limiting obstacles or terrain, APG will initially evaluate the published SIDs, ODPs, or even the missed approach procedures for the chosen runway. If these procedures do not provide relief from the limiting obstacle/terrain, APG will then develop tailored Engine-Out Departure Procedures.
What are TORA, TODA, ASDA, and LDA, and how are they used in an APG runway analysis?
Declared distances represent the maximum distances available and suitable for meeting takeoff, rejected takeoff, and landing distances performance requirements for turbine powered aircraft. The declared distances are TORA and TODA, which apply to takeoff; Accelerate Stop Distance Available (ASDA), which applies to a rejected takeoff; and Landing Distance Available (LDA), which applies to landing. A clearway may be included as part of the TODA, and a stopway may be included as part of the ASDA. (AC 150/5300-13A paragraph 323.a.)
The actual definitions for each are outlined in 14 CFR Part 1, and also in AC 150/5300-13A paragraph 323.c.(1) as quoted below:
1. The takeoff decision speed (V1), and the following distances to achieve or decelerate from V1 are established by the manufacturer and confirmed during certification testing for varying climatological conditions, operating weights, etc.:
a) Takeoff run — the distance to accelerate from brake release to liftoff, plus safety factors. (See TORA, paragraph 323.d(1).)
b) Takeoff distance — the distance to accelerate from brake release past lift-off to start of takeoff climb, plus safety factors. (See TODA, paragraph 323.d(2).)
c) Accelerate-stop distance — the distance to accelerate from brake release to V1 and then decelerate to a stop, plus safety factors. (See ASDA, paragraph 323.d(3).)
d) Landing distance — the distance from the threshold to complete the approach, touchdown, and decelerate to a stop, plus safety factors. (See LDA, paragraph 323.e(1).)
For takeoff, APG analyzes the TORA, TODA, and ASDA distances. How these are handled varies depending on whether the aircraft’s One-Engine Inoperative (OEI) performance data is given as balanced or unbalanced field length data. In a balanced field length aircraft, there is no differentiation between accelerate-stop and accelerate-go distances. In an unbalanced field length aircraft, the accelerate-go and accelerate-stop distances are evaluated separately as a function of the V1/VR ratio and, thus, can be optimized for the particular scenario.
If the aircraft is balanced, the maximum distance available for takeoff — whether the takeoff is continued or rejected — is the lesser of the TORA, TODA, and ASDA. Since the accelerate-go and accelerate-stop distances are balanced and, thus, equal to the field length required, exceeding any one of these three values would result in a longer field length required than available.
If the aircraft is unbalanced, the maximum distance for takeoff is separated on the basis of whether the takeoff was rejected or continued. If the takeoff is continued, the distance used will be the TORA, plus any clearway up to the maximum clearway allowed. The maximum clearway allowable for use in calculating takeoff distances is defined in CFR 25.113 (c) (1) (i).
For takeoff on wet runways, whether the aircraft is balanced or unbalanced, no clearway may be considered for takeoff. This means the aircraft must achieve the reduced 15 ft. screen height by the end of the TORA. In addition, the use of reverse thrust may be considered for wet runway performance.
For more information on the use of declared distances for takeoff in a One Engine Inoperative Runway Analysis, please refer to the performance section within CFR Part 25 (sections 101 thru 123).
Landing is a bit simpler, as the landing distance required must not be greater than the landing distance available, or LDA (refer to CFR Part 25.125). The landing distance required is based upon crossing the threshold at an altitude of 50 ft. to a normal touchdown, maximum braking to a full stop.
What if the ASDA is shorter than the TORA?
Some airports, especially in the United States, have an Accelerate Stop Distance Available (ASDA) that is shorter than the Takeoff Run Available (TORA). This is because the end portion of the runway is not available for accelerate-stop distance calculations, usually as a result of unacceptable land use in the Runway Protection Zone (RPZ) beyond the departure end of the runway. The FAA requires that there be a minimum “safety area” beyond the departure end of the runway that is protected from infringement by items on the ground. This can include roads, buildings, farmland (that does not meet specific requirements), etc. More information can be found in AC 150/5300-13A paragraph 310 as to the requirements of this RPZ.
In the case of Teterboro (KTEB), at the time of this writing, there is an ASDA that is 910 ft. shorter than the TORA on runway 01. This equates to an ASDA of 6,090 ft. Many charts and FMS databases in print today make no mention of this and simply show a runway length of 7,000 ft. with no restrictions to takeoff distance. This gives the illusion that the full 7,000 ft. is available for takeoff when, in fact, it is not.
The effect this has on performance will vary depending on whether the aircraft performance data given is balanced or unbalanced. If the aircraft is balanced, the maximum distance allowed for takeoff will be limited by the reduced ASDA. This is because a balanced aircraft, by definition, will have accelerate-stop and accelerate-go distances that are equal (in most cases), and the calculated field length required must be less than or equal to the Accelerate-Stop Distance Available. If the aircraft is unbalanced, the aircraft must have an accelerate-stop distance that is shorter than the ASDA, but the accelerate-go distance may exceed the ASDA. The maximum distance allowed for accelerate-go will be the TORA plus any clearway, up to the maximum clearway allowed. Refer to the FAQ describing ASDA, TODA, and TORA for further clarification on the use of clearways.
At the time of this writing, over 250 airports in the United States have an ASDA that is shorter than the TORA. Some of the larger airfields include, but are not limited to, the following:
- Albany Intl (KALB)
- Anchorage Intl (PANC)
- Atlanta Intl (KATL)
- Cheyenne Regional (KCYS)
- Chicago O’Hare Intl (KORD)
- Dallas Love (KDAL)
- Fresno Intl (KFAT)
- Gen Mitchell Intl/Milwaukee Intl (KMKE)
- Honolulu Intl (PHNL)
- McCarran Intl/Las Vegas (KLAS)
- Miami Intl (KMIA)
- Minneapolis St. Paul Intl (KMSP)
- Niagara Falls Intl (KIAG)
- Orlando Intl (KMCO)
- Peoria Intl (KPIA)
- Philadelphia Intl (KPHL)
- Pittsburgh Intl (KPIT)
- Prescott (KPRC)
- Rochester Intl (KROC)
- San Diego Intl (KSAN)
- San Francisco Intl (KSFO)
- Savannah/Hilton Head Intl (KSAV)
- St. Louis Intl (KSTL)
- Tampa Intl (KTPA)
- Teterboro (KTEB)
If an aircraft weight is less than the approach climb limit on the landing analysis and a missed approach is commenced, is the crew to comply with the Special Departure Procedures, or are they safe to fly the published missed approach?
The approach climb limits published on all APG landing gross weight charts are taken directly from the approach climb (landing WAT) information in the AFM. The only regulatory requirement from initial aircraft certification is that the two engine aircraft is able to maintain a 2.1% climb gradient in the missed approach configuration of gear-up, one engine inoperative, go around power, and flaps. This requirement is independent of the approach/missed approach being flown and any obstacle or terrain considerations.
Therefore, there is no consideration of obstacle clearance for the missed approach being flown.
Many airlines do recommend flying a takeoff Engine-Out Departure Procedure as the missed approach if there is one available for the runway in use; they also recommend that pilots train in those scenarios. It seems better to follow a procedure where obstacle or terrain clearance has been considered than not.
Keep in mind that if you do intend to fly the takeoff Engine-Out Departure Procedure for a missed approach, the takeoff Engine-Out Departure Procedure would commence at the departure end of the runway and not necessarily from the missed approach point, which may be quite a distance from the arrival end of the runway.