In the world of aviation, there is a golden rule known to every pilot: “A landing is just a bonus; the go-around is the primary option.” However, in the high-pressure environment of commercial operations, psychological factors such as “Get-there-itis” often clash with safety protocols.
Today, we are conducting a deep-dive analysis of a real-world event: an approach into Ho Chi Minh City (SGN). This case study is a textbook example of how a combination of high energy, strong tailwinds, and automation mismanagement can lead to an Unstable Approach. By dissecting this event, we aim to understand the critical importance of Energy Management, CRM (Crew Resource Management), and the courage to execute a Go-Around.
1. The Scenario: A Race Against Energy
Let’s reconstruct the timeline of the event. The aircraft was performing an arrival procedure into Tan Son Nhat International Airport (SGN), specifically aiming for Runway 25R.
The Setup: High and Fast at SOKAN
As the aircraft approached the waypoint SOKAN, the warning signs were already present. The Pilot Monitoring (PM) correctly identified that the aircraft was “High on profile” relative to the descent path. In response, the Pilot Flying (PF) reduced speed and selected Flaps 1.
However, at 6,000 feet, the speed was still selected at 200 knots. Crucially, despite being high, no speed brakes were used to dissipate the excess energy. This was the first missed opportunity to regain the profile.
The Tailwind Trap
Approaching 15NM (Nautical Miles) from the threshold at 5,600 feet, the aircraft remained 1,000 feet above the ideal descent profile. The situation was aggravated by a significant environmental factor: a 20-knot Tailwind.
A tailwind pushes the aircraft forward, increasing its ground speed. To maintain a standard 3-degree glide path with a high ground speed, the aircraft requires a much higher Rate of Descent (ROD). Without drag devices (Speed Brakes or Gear), the aircraft simply could not descend fast enough.
Critical Data Point: Passing 4,600 feet, the aircraft was 1,500 feet above the profile with the tailwind increasing to 24 knots. The energy state was becoming critical.
2. Automation Confusion and Leadership Breakdown
Realizing the aircraft was not capturing the path, the crew armed the approach mode. The aircraft captured the Localizer (LOC*) at 4,200 feet. The crew attempted to manage the descent using OP DES (Open Descent) mode and finally extended the speed brakes.
The “Glideslope from Above” Error
At 2,000 feet, seeing the unstable situation, the Captain (CAPT) intervened and took control of the aircraft. The Captain attempted a maneuver known as “Glideslope Interception from Above.”
This is a valid but advanced maneuver. The Captain selected a Vertical Speed (V/S) of -2,000 feet per minute (fpm) to dive down to the glide path. However, a critical automation error occurred: The crew failed to set a higher altitude in the FCU (Flight Control Unit).
For the autopilot to capture the Glideslope from above, the FCU altitude must usually be set above the current aircraft altitude to arm the mode correctly. By leaving the FCU at 1,000 feet, the automation logic was confused. Although G/S* was eventually captured at 1,600 feet, the maneuver was executed poorly and late.
The Configuration Rush
Because of the high speed and altitude, the aircraft configuration was dangerously delayed.
Flaps 3 were only extended after G/S capture at 1,600 feet.
Config FULL (Landing Flaps) was only set around 1,200 feet.
This “rushed” configuration increases the workload in the cockpit and reduces the crew’s capacity to monitor the primary flight parameters.
3. The “Stable” Callout: Reality vs. SOP
The most defining moment of this incident occurred at 1,000 feet AAL (Above Aerodrome Level). In modern aviation, 1,000 feet is the standard “Stabilization Gate” for Instrument Meteorological Conditions (IMC), and often for VMC as well.
The Stabilization Criteria (SAC)
According to standard SOPs (Standard Operating Procedures), to be considered “Stable” at 1,000 feet, the aircraft must meet the following criteria:
- On the correct flight path (Localizer and Glideslope).
- Speed within Vapp +10 knots to Vapp -5 knots.
- In the landing configuration (Gear Down, Flaps Full).
- Thrust stabilized above idle (usually ~40% N1 or higher).
The Reality of the Event
At 1,000 feet, the Captain called out “Stable.” However, let’s look at the data:
- Indicated Speed: 158 knots (Vapp was 140 knots). This is Vapp + 18 knots.
- Thrust: IDLE.
- Tailwind: 5 knots.
The aircraft was NOT stable. It was excessively fast, and the engines were at idle power. An engine at idle takes several seconds to “spool up” if a Go-Around is needed, creating a dangerous vulnerability near the ground.
The “Stable” callout by the Captain was a clear example of Confirmation Bias—seeing what he wanted to see to justify continuing the landing.
4. Root Cause Analysis: Why did this happen?
This incident wasn’t caused by a technical failure, but by Human Factors.
| Deficiency | Analysis |
| Situational Awareness | The crew failed to appreciate the effect of the strong 24kt tailwind. They applied a “Decelerated Approach” technique (slowing down later) which is only suitable for headwinds or calm winds. They were “behind the aircraft.” |
| Automation Management | The PM took control but executed the “G/S Intercept from Above” procedure incorrectly (FCU altitude error). This highlights a lack of understanding of the aircraft’s auto-flight logic under stress. |
| CRM & Leadership | Task sharing broke down. The PM became the PF abruptly. Crucially, there was a lack of Assertiveness. The other pilot likely knew they were unstable but did not challenge the Captain’s “Stable” callout. |
| Decision Making | The reluctance to perform a Go-Around. This is the most dangerous mindset in aviation. The crew prioritized landing over the stabilization criteria. |
5. Mitigation Strategies: How to Prevent Recurrence
Safety is about learning. Here are the key takeaways and mitigation actions for pilots facing similar scenarios.
1. The TEM Briefing (Threat and Error Management)
The approach briefing must be more than a formality.
“We have a 20-knot tailwind on arrival.” -> Mitigation: “We will configure early. We will be fully established by 2,000 feet. If we are not at 180kts by 6NM, we will go around.”
2. Respect the Speed Gates
Energy management is mathematical. Pilots should adhere to specific “Gates” to ensure they are on track:
- 6 NM: Max 180 knots.
- 5 NM: Max 170 knots.
- 4 NM: Max 160 knots.
If you miss a gate, you are already unstable. Acknowledge it and correct it immediately, or discontinue the approach.
3. Assertive Callouts
Crew members must be empowered to speak up. A callout of “Speed High” or “Unstable” is not a criticism of the pilot flying; it is a safety barrier. If the Captain calls “Stable” when the aircraft is Vapp+18 and Idle, the PM must reply: “Unstable, Go Around.”
4. The Go-Around Mindset
Pilots must remain “Go-Around Minded” until the thrust reversers are deployed. A Go-Around is never a failure; it is a successful maneuver that avoids a potentially catastrophic unstable landing. In this SGN case, a Go-Around at 2,000 feet or even 1,000 feet would have been the safest and most professional decision.
Conclusion: Flying the Aircraft, Not the Schedule
The arrival into Ho Chi Minh City serves as a powerful reminder of the physics of flight. You cannot cheat energy. A 24-knot tailwind combined with a high profile requires aggressive drag management and early configuration. Reliance on automation to “fix” a bad profile often leads to further saturation and errors.
For aspiring pilots and seasoned aviators alike, the lesson is clear: Monitor your energy, respect the stabilization criteria, and never hesitate to Go Around. The runway will always be there for a second attempt.
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