Friday, January 20, 2017

SAVE: Surveillance alarm ADS-B state Verified against Expected state for clearance and procedure

Surveillance alarm triggered by
ADS-B aircraft state
Verified against
Expected aircraft state for clearance and procedure

ADS-B reports are available at the instant that the data is transmitted.

Real-time surveillance can be integrated with sophisticated algorithms to trigger awareness of significant event transpiring in real-time.  These tools can be applied local to an airport, or centralized through a network of receiving stations.

Aircraft state, including ground speed, baro altitude, and Position reports; from arriving airplanes can be compared against preceding flights from other aircraft, including those landing immediately in advance, and also for the same or specific airplanes arriving regularly.

Any approach may result in deviating from the assigned path.

Landing long means that the airplane did not touch down in the expected landing zone, or is not slowing down sufficiently to stop without overrun.

Landing long reduces the available runway length to stop the airplane.

Landing long may require utilizing maximum braking and reverse thrust.

In spite of efforts, landing long may result in an overrun.

When landing long, there are two courses of action:
  1. Land, apply maximum braking
  2. Go-Around, climb
An arriving airplane should touch down in an expected zone.

An airplane that lands beyond the expected touchdown zone can be monitored for braking action.

Every airplane can be monitored for trends.

The point at which the airplane speed and position dictate a go-around can be calculated in real-time.

For discussion, a rule of thumb is an arriving airplane is traveling around 150 knots is traveling about 250 feet per second.

It takes 20 seconds to travel about 5,000 feet; or about midfield on a typical runway.

A decisive response to go-around when failing to touchdown 20 seconds after crossing the runway threshold would normally be recommended.  

ADS-B monitoring can trigger a response to direct a missed approach in time for the airplane to safely go-around.

An airplane that has touched down, but without reducing ground speed sufficiently when crossing a set point on the runway, should immediately go-around.

ADS-B monitoring can trigger a response to direct a missed approach if an airplane on the ground not slowing down sufficiently.  

Recent aircraft incidents include an airplane that "floated" long and failed to Go-Around properly, an airplane that landed long and overran the runway, an airplane that flew well above and beyond the approach glide slope.

Winds aloft can be observed by airplane maneuvering.

Wind shears can be observed, their risks can be managed or minimized.

Tail-wind conditions can be detected and flight crews can be notified in real-time, with greater awareness of their susceptibility to landing long.

Extending ADS-B to include airspeed, power settings, flap/gear configuration; adds considerably to what types of alarms can be raised.


A single board computer and radio interface can gather local airplane position sufficiently to create situational awareness of airplane expected operating states.

Trend monitoring can reveal diversions from the crowd behavior or otherwise expected behavior.

Alarms can be raised in real-time when tail wind conditions, or significant wind-shears, are encountered.

Alarms can be raised in real-time when diversions from expected behavior encounter missed approach criteria.

Alarm conditions may include landing long scenarios, such as failure to touch down within an expected zone, or failure to slow to an expected speed by a certain point on the runway.

A response to an alarm can provided to Air Traffic Control or Tower Controllers for their consideration in relaying to the affected flight crews.

A response to an alarm can be provided directly in the form of text to speech triggered on Air Traffic Control frequency (Tower/Approach).

Automated text to speech can include specific information directed to a specific flight or airplane, such as tail number or flight number.

Expected airplane performance can be modeled, most simply by building expertise over the course of time with scheduled airplane traffic.

A local receiver/processor/transmitter could autonomously operate given a source of power.

A local receiver can communicate with a remote server to access more sophisticated or relevant modeling of expected behaviors.

A local receiver can be programmed locally to operate without real-time contact to a remote server, using stored expected behavior, monitoring of all radio relevant local radio transmissions, access to local weather condition data, and a data base built from all prior traffic organized for relevance to current conditions and aircraft.

NOTE: I am hoping that SAVE initiatives remain in the public domain.  I am sharing all of my thoughts freely for this to encourage creative contributions from anyone and stave off any enterprise laying claim to this as IP or patentable

Stay tuned!

Peter Lemme
peter @

Follow me on twitter: @Satcom_Guru

Copyright 2017     All Rights Reserved

Peter Lemme has been a leader in avionics engineering for 35 years. He offers independent consulting services largely focused on avionics and L, Ku, and Ka band satellite communications to aircraft. Peter chairs the SAE-ITC AEEC Ku/Ka-band satcom subcommittee developing PP848, ARINC 791, and PP792 standards and characteristics. 

Peter was Boeing avionics supervisor for 767 and 747-400 data link recording, data link reporting, and satellite communications. He was an FAA designated engineering representative (DER) for ACARS, satellite communications, DFDAU, DFDR, ACMS and printers. Peter was lead engineer for Thrust Management System (757, 767, 747-400), also supervisor for satellite communications for 777, and was manager of terminal-area projects (GLS, MLS, enhanced vision).

An instrument-rated private pilot, single engine land and sea, Peter has enjoyed perspectives from both operating and designing airplanes.  Hundreds of hours of flight test analysis and thousands of hours in simulators have given him an appreciation for the many aspects that drive aviation; whether tandem complexity, policy, human, or technical; and the difficulties and challenges to achieving success.

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