A Bombardier Challenger 300, N300ER, encountered an upset when the flight crew disconnected the autopilot while suffering from a nose-up mistrim situation. The mistrim was the result from a failure of the autopilot stabilizer trim control. The upset resulted in a roller coaster exceeding +4g and -2g, eventually brought under control by the flight crew. Tragically, a passenger was fatally injured in the upset.
Satcom Guru
L band, Ku band, Ka band: Aeronautical Applications, DO-160 Qualification, Certification, Regulation, and Standardization; Modeling; Testing; Cellular; Bluetooth; WiFi; Antenna; Beam Steering; Aero Performance - CFD; Link Budget;
Saturday, March 25, 2023
Severe Stabilizer Mistrim - Pitch Upset - Challenger 300 N300ER - One Fatality
Tuesday, March 14, 2023
Satshow 2023 Tuesday - The Exhibit Hall is Open!
Satshow 2023 is a gathering of service providers, equipment suppliers, technology wizards and a reunion of the many people involved in satellite communication. Held once again in the Washington Convention Center, the show runs four days long: Monday dedicated to lectures and an exhibit hall open Tuesday through Thursday, with speakers continuing alongside.
Monday, February 20, 2023
Engineer Week - 2023
I was asked to speak to a group of engineers today. Here were the questions I was asked and my talking points. What did I miss?
Monday, January 30, 2023
Sunday, November 20, 2022
Goodbye Twitter - Where to go now?
I have deleted my account on Twitter (satcom_guru).
While I cannot support the platform, I am anxious to support the community that I have grown so fond of. This is my list of who I enjoyed from hearing from, learned from, or inspired me to jump into a new rabbit hole. This post will be updated frequently.
I intend to stay here on this site, but may also post occasionally at LinkedIn.
Friday, November 11, 2022
SJ182 A Sequence to Tragedy
On 9 January 2021, a Boeing 737-500 aircraft, registration PK-CLC, was on a scheduled domestic flight, from Soekarno-Hatta International Airport (WIII), Jakarta, to Supadio International Airport (WIOO), Pontianak. PT Sriwijaya Air flight SJ182 crashed into the sea about five minutes later, with all 62 lives lost in the tragedy. Weather conditions for the mid-afternoon flight were not considered a factor.
The Captain was the pilot flying (PF). The 54 year old Captain had nearly 18,000 flight hours, over 9,000 in the 737. The 34 year old First Officer, pilot managing (PM), had over 5,000 flight hours, virtually all on the 737.
KNKT, Komite Nasional Keselamatan Transportasi is the Indonesia Independent Investigation Authority also known as National Transportation Safety Committee / NTSC) released the final accident report on 10 Nov 2022.
Wednesday, June 30, 2021
Elon Musk Starlink Update MWC2021
Monday, March 1, 2021
Sunday, January 10, 2021
Sriwijaya Air flight SJ182
Sriwijaya Air flight SJ182 crashed shortly after take off from Jakarta on 9 January 2021. The flight, operated by 737-500 registered PK-CLC, departed at 07:36 UTC (14:36 local time). The last ADS-B signal from the aircraft was received by Flightradar24 at 07:40 UTC (flightradar24.com).
The airplane appears to be destroyed on impact with all 62 lives lost.
Sorrow for the victims and for those that loved them.
Sunday, January 3, 2021
Mid-Value Select (MVS): Goldilocks in the House of MCAS
Angle of Attack (AoA) is measured on the 737MAX using two AoA vanes, one installed on the left side of the airplane and the other on the right side. While each AoA vane is calibrated and precise, inferring AoA directly overlooks local aerodynamic factors that can cause the sensor reading to diverge from the desired value, notably with sideslip. A tolerance exists from what the AoA vane senses and the expected value. The question arises, how to manage AoA sensor tolerances or undesired behavior to maximize availability of desired functionality, while limiting exposure to undesired hazards?
Friday, October 23, 2020
Monday, June 22, 2020
FANS - 25 year Anniversary
Monday, March 9, 2020
Elon Musk Keynote - Satellite 2020
- innovation is insufficient
- the sign of success is not going bankrupt
- focus on achieving something soon, if the schedule is wrong, the design is wrong
- the bigger the rocket the more affordable the service
- learning is inherently accessible to everyone
Friday, February 28, 2020
The Third-Generation of Broadband Aeronautical Satellite Communications
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Additional Modem Unit |
Monday, October 28, 2019
Flawed Assumptions Pave a Path to Disaster
Boeing had declared MCAS malfunction a MAJOR hazard.
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JT610 Final Report |
The answer lies in a number of buckets, which overflow beyond just MCAS:
- a desire to justify design rather than direct safety
- over-use of a convenient test condition restriction
- blind reliance on unproven pilot response
- misunderstanding the ramifications from removing an under-appreciated safety interlock
- ignoring escalation from the combination of persistent hazards
- incorrectly applying a convenient probabilistic factor to dodge the obvious conclusion
- overlooking the ramifications from extending Speed Trim to provide Stall Identification
Friday, September 27, 2019
AEEC Ku/Ka Satcom Subcommittee - Sep 2019 Meeting Report
Topics discussed included:
- Smaller form-factor antenna
- Thermal management of solid-state antennas
- Replaceable/Multiple Modems
- Standard Ka/Ku-band Antenna
- Enhanced Terminal Security
- Enhanced Network Security
- IF/RF over Fiber (modem to antenna)
- Baseband over Fiber (modem to antenna)
- Additional radios under the radome
Tuesday, September 24, 2019
737 AoA and Redundancy
Monday, September 2, 2019
Postcards from Destination Moon: The Apollo 11 Mission
Wednesday, August 21, 2019
Connecting the Dots: From Command to Action
- Manual trim (by trim wheel) has highest priority
- Electric trim has second priority
- Autopilot trim has lowest priority
- Significant column aft movement shall inhibit airplane nose down trim commands
- Significant column fwd movement shall inhibit electric airplane nose up trim commands
- Two cutout switches are used together to remove both Electric and Autopilot trim commands
- Stabilizer travel shall be limited to the same point during airplane nose up motion
- Stabilizer travel shall be limited using to an intermediate point while flaps up, using electric trim
- to limit the nose down runaway mistrim
- Stabilizer travel shall be limited using autopilot airplane trim nose down to the flaps down limit
- autopilot "in command" stab trim objective is to maximize elevator authority
- Stab Trim fail indicator provided if trim ineffective
- NG FCC speed trim schedule was extended to stall speeds, to facilitate stall recovery
- Speed Trim fail indicator if command does not match monitor command
- Fast Electric trim speed is selected when flaps-not-up
- FCC fast trim speed is commanded by FCC based on flaps down
Monday, July 29, 2019
Movable Stabilizer
The fuselage itself can contribute to pitch-up at high angles of attack. An example of that can be related to the 737MAX engine nacelles (or pods).
Gen. Chuck Yeager credited the trimmable stabilizer as the key technology for dealing with Mach Tuck, or shifting the lift aft with supersonic speeds causing a pitch down. While Mach Tuck is managed separately, the principal objective with a trimmable stabilizer is to minimize drag along with maximizing the elevator for whatever flight condition or center of gravity.
Various regulatory factors are listed at the end.
Saturday, May 18, 2019
737 Pitch Trim Incidents
With sparse reporting to draw from, it can be surmised that a stabilizer runaway or failure occurs about once a month, with a jam about once a year (world-wide). Just plugging this into a spreadsheet yields the failure rate for runaway, loss of function and jam. I am just assuming about 5,000 737 during the time frame for the failures accounted for, and looking ahead with a larger fleet size.
Thursday, May 16, 2019
The Beat Goes On
Sunday, April 7, 2019
What happened on ET302?
Tuesday, April 2, 2019
Trim Cutout with Severe Out-of-Trim Stabilizer can be difficult to recover
One possible explanation is that the loads on the jackscrew due to the severe stabilizer nose down out-of-trim situation were too great for the pilot to overcome using the trim wheel with folding handle. The pilots restored electric trim as a means to trim.
Boeing published a technique in the past that discussed this issue and the need to release the column briefly in a series of "roller coaster" or "yo yo" maneuvers, by cranking in stabilizer trim alternatively with large column commands.
This is in a 737NG Flight Crew Ops Manual
This is in the 737NG training manual:
Manual Stabilizer TrimIf manual stabilizer trim is necessary, ensure both stabilizer trim cutout switches are in CUTOUT prior to extending the manual trim wheel handles.Excessive airloads on the stabilizer may require effort by both pilots to correct the mis-trim. In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually.Anticipate the trim changes required for the approach. Configure the airplane early in the approach. When reaching the landing configuration, maintain as constant a trim setting as possible. If a go-around is required, anticipate the trim changes as airspeed increases.This is in a 737 QRH (Ref 9.15)
Thursday, March 28, 2019
AoA Vane must have Failed, the Boeing Fix is In, Senate Grills FAA
Wednesday, March 27, 2019
How Did MCAS Get Here and What Hurdles Remain?
“A single point of failure is an absolute no-no,” said one former Boeing engineer who worked on the MAX"
"Rick Ludtke, a former Boeing engineer who worked on designing the interfaces on the MAX’s flight deck, said managers mandated that any differences from the previous 737 had to be small enough that they wouldn’t trigger the need for pilots to undergo new simulator training."
"He said that if the group had built the MCAS in a way that would depend on two sensors, and would shut the system off if one fails, he thinks the company would have needed to install an alert in the cockpit to make the pilots aware that the safety system was off. And if that happens, Ludtke said, the pilots would potentially need training on the new alert and the underlying system. That could mean simulator time, which was off the table."
"Matt Menza, a former Boeing pilot who worked on the MAX, said that during flight testing of planes ready for delivery, he wasn’t aware of any events that indicated a problem with the stall warning or the MCAS system. But he said an ideal system would have been built on two angle-of-attack probes, so that a single bad value wouldn’t cause problems. Menza and two other pilots who have worked on the MAX said they were unaware that the system used only one AOA probe."
Sunday, March 24, 2019
Taking the Next Steps while Awaiting on the Preliminary Report from ET302
Tuesday, March 19, 2019
Ethiopian ET302 similarities to Lion Air JT610
With this in mind, what are the issues left to restore 737 MAX airworthiness?
Friday, March 15, 2019
What have we learned this week?
Thursday, March 14, 2019
Comparing Ethiopian ET302 to Lion Air JT043, JT610
Tuesday, March 12, 2019
Atlas Air 5Y3591 Dove because of Nose-Down Elevator Command
Saturday, March 9, 2019
Exploring Rain Fade in an Extreme Rain Fall Zone
Friday, March 8, 2019
5Y3591 Stabilizer Trim Actuator appears to be Nose Down

Thursday, March 7, 2019
Limiting RF exposure to Humans in Close Proximity to Satellite Transmitters
Wednesday, February 27, 2019
More Questions Raised for Atlas 5Y3591 Loss of Control
Sunday, February 24, 2019
NTSB Brief Atlas 5Y3591 Sun 4pm CST
Saturday, February 23, 2019
Atlas Air 767 Flight 5Y3591 Plunges from 6,000 Feet
Friday, December 7, 2018
Stopping Distance
- A 10 knot tailwind adds about 21% to the stopping distance
- A wet runway adds about 15% to the stopping distance
- Standing water can more than double stopping distance.
Lateral approach path shows a correction right-to-left on short final, which may have led to running off the left side of the runway. The last recorded speed of 49 knots at the runway end, after a normal arrival point, and expected touchdown point (assuming appropriate landing weight), leaves standing water/hydroplaning as the most likely overrun villain. There is no data to confirm the reason for lack of deceleration and control; only data to show it did not (which is evident in its final resting position). The nose-gear entered the EMAS probably traveling between 35 and 40 knots.
Sunday, December 2, 2018
Angle of Attack Vane Failure Modes
Friday, November 23, 2018
First Look at JT610 Flight Data
The captain seems to have taken control back in the end, and pulls the column hard aft. MCAS is able to trim yet another one unit nose down before the captain stops it, but there is no subsequent significant command to trim stabilizer nose up. The airplane dive exceeded 450 knots by the point of impact.
Search for the CVR continues.
Tuesday, November 20, 2018
737 FCC Pitch Axis Augmentation - Command Integrity Mandate for Dual Channel, Fail-Safe
Thursday, November 15, 2018
737 MCAS - Failure is an Option
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MCAS Commanded Stabilizer Trim Without Stopping |
Monday, November 12, 2018
Stabilizer Trim
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http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/83ec7f95f3e5bfbd8625833e0070a070/$FILE/2018-23-51_Emergency.pdf |
Saturday, October 13, 2018
Coverage Along a Route - Europe
Friday, October 12, 2018
Close Calls Coming (TG679) and Going (IX611)
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IX611 Takeoff normal (A) and accident (X) |
Friday, September 28, 2018
Using True Time Delay to Increase Instantaneous Bandwidth in a Phased Array Antenna
Tuesday, September 25, 2018
APEX 2018 Midway Report
Thursday, September 20, 2018
Panasonic adds Inmarsat GX to the Routing Table
- Panasonic will offer Inmarsat as their exclusive Ka-band satcom supplier
- Panasonic will continue to operate and grow their Ku-band network
- Inmarsat will be able to bundle in Panasonic IFE and support as a part of their offerings
- Panasonic and Inmarsat will jointly develop a new Inmarsat GX terminal
Thursday, June 7, 2018
Aviation Cybersecurity 101
Here is my slide deck (with notes). I have revised and added a slide to address how an iPad can host type B EFB messages.
Monday, April 30, 2018
Lion Air PK-LOO JT-892 Departed runway after touchdown
Monday, February 26, 2018
Seamless Air Alliance - Who Owns the Customer?
A participating airline picks parts from a catalog, installs per a cookie-cutter, turns it on, and the passengers connect to the Internet.
Friday, February 9, 2018
Malfunction in an Aero Ku/Ka-band Satcom System
No failure of the satcom system should create an unsafe effect.
Users of the satcom system do so at their own peril, as they would with any Internet access provider.
Discovery of cybersecurity vulnerabilities should emphasize rapid response to close the threat and a cooperative approach to sharing information privately, with an agreement to share enough information publicly to raise awareness of best practices.
Details and a checklist in the following paper.
Sunday, January 28, 2018
PP792 Mark 2 Satcom Advanced Features
Significant advancements include:
- Single, standard installation, no customization, fully interchangeable
- Smaller: no KRFU, Virtual APM
- Lighter: smaller connectors, fewer wires, no hyper-critical wiring, coax, or waveguide
- Flexible lug pattern accommodates two apertures, each up to 42"
- High power supply (2000 Watts) for large, solid-state, phased-array antennas
- Integrated Position, Attitude and Heading sensor
- High performance IF interface supporting NGSO networks
Sunday, January 14, 2018
Thursday, January 11, 2018
10 Years Later - Still Standardizing Aero Ku/Ka Satcom
Tuesday, January 2, 2018
Regulating Radiated Emissions
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https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet56/oet56e4.pdf |
Wednesday, December 6, 2017
Project Paper 792 - Dec 2017 Update
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Project Paper 792 System |
Project Paper 792 provides the form and fit of these second-generation satcom systems building on the baseline from ARINC 791 part 1 and using a common functional definition using ARINC 791 part 2 and Project Paper 848.
Friday, November 17, 2017
Comparing Antenna Performance
The ThinKom antenna can operate without any performance reduction due to skew angles that may be encountered in the tropic regions, unlike a 2-axis antenna which may suffer severe degradation.
Theoretically, these same benefits await other flat-panel antennas. Practically, no other antenna has made public, legitimate claim to a design matching instantaneous bandwidth, efficiency, robustness, and scan loss, in the same size package. VICTS weakness is cost, weight, form-factor; all of which electronic phased array may have advantage.
Monday, November 13, 2017
Defense in Depth
Friday, October 27, 2017
Space Shuttle Approach and Landing Test Program
Monday, October 23, 2017
Google Loon - Floating Nest of Radio Technologies
Saturday, September 2, 2017
Managing Network Security and QoS: PP848
Friday, September 1, 2017
“Otto”, your new First Officer
Thursday, August 31, 2017
Antenna Performance along an Airline Route
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Skew angle and Elevation angle from various satellite positions, flying Los Angeles to Sao Paulo, Multi-gimbal antenna |