Visibility Required for Taking Off and Landing an Aircraft

February 14th, 2025 - 9 min read
Visibility Required for Taking Off and Landing an Aircraft

For a flight to take off, there must be visible weather conditions in atleast three airports–the takeoff location, the destination airport, and a buffer airport on the way or close by the flight route in case of any emergency and sudden need for an emergency landing. 

Much of the takeoff and landing parts of a flight depend on the visibility. Pilots rely on clear visibility to make accurate decisions, especially during core phases of flight. The visibility needed to land a plane varies depending on the airport, weather conditions, and the equipment onboard the aircraft. In this article, we will explore the concept of visibility in aviation, its types, and the specific visibility requirements for airports in Nepal, while reflecting on the visibility of Bhairahawa Airport, the visibility of Kathmandu Airport, and the visibility of Pokhara Airport.

Visibility in Nepal Aviation

The one-of-a-kind diverse Nepali geography with tall mountains and deep valleys, comes with its fair share of challenges to aviation. This makes visibility a major factor for both takeoffs and landings. The country’s airports, especially those located near mountainous regions, demand precise visual and instrument-based navigation. Poor visibility in aviation is often caused by fog, rain, windy storms, or haze, which are common during certain seasons in Nepal.

The visibility of Kathmandu airport is affected by its location in a valley, where fog and haze can significantly reduce visibility, especially in winter. While the visibility of Pokhara airport can vary due to its proximity to the Annapurna range. Pilots must navigate through mountain terrain, making clear visibility essential. On the other hand, being located in the Terai region, the visibility of Bhairahawa airport is often better than mountainous airports, but it can still be impacted by seasonal fog.

Types of Visibility in Aviation

Frequent weather changes, especially in monsoon and winter seasons, can lead to low visibility in aviation, causing delays and diversions at key airports like Tribhuvan International Airport (TIA) in Kathmandu, Gautam Buddha International Airport (GBIA) in Bhairahawa, and Pokhara International Airport (PIA). To understand the visibility needed to land a plane, three different types of visibility in aviation are considered.

1. Runway Visual Range (RVR)

Runway Visual Range (RVR) is the distance a pilot can see down the runway while still on the ground. This measurement is crucial for takeoffs and landings, particularly in foggy or rainy conditions. In Nepal, where morning fog is common in the Terai region (e.g., Bhairahawa and Biratnagar airports), RVR is closely monitored.

  • Kathmandu International Airport (TIA) often experiences reduced RVR due to haze and smog, especially in winter.

  • Bhairahawa Airport frequently faces low visibility in aviation due to thick morning fog, affecting early flights.

  • Pokhara Airport can have fluctuating RVR values due to rapid weather shifts influenced by nearby hills and lakes.

Airports in Nepal have installed advanced Instrument Landing Systems (ILS) at some runways to assist pilots in poor visibility conditions.

2. Meteorological Visibility

Meteorological visibility refers to the distance a pilot can see natural or artificial objects, such as terrain, buildings, or other aircraft. In Nepal, meteorological visibility comes to play often since most airports are surrounded by mountains or located in valleys.

Kathmandu Valley’s weather can cause rapid changes in visibility, with smog reducing clarity during winter and heavy monsoon rain impacting flights.

The Himalayan region (e.g., Lukla Airport) has extremely variable meteorological visibility. Clear conditions can suddenly turn foggy, making operations unpredictable.

Pokhara Airport experiences mist and haze, especially in the early morning, impacting meteorological visibility.

Weather forecasts help in determining whether flights can operate safely, as unpredictable conditions in Nepal can lead to diversions or cancellations.

3. Slant Visibility

Slant visibility is the visibility observed from the cockpit, particularly during the approach and landing phases. This is crucial for pilots to identify the runway and its surrounding environment. In mountainous airports like Lukla, Jomsom, and Simikot, slant visibility is significantly affected by sudden cloud formation. Pilots often rely on visual flying rules (VFR) since instrument landing is not available at these airports.

Also learn: The Difference between VFR and IFR Flying Explained

Pokhara and Bhairahawa airports benefit from relatively flat terrain, but slant visibility is still affected by morning mist and monsoon rain.

Kathmandu Airport faces challenges due to its location in a valley, where clouds and haze can reduce slant visibility, requiring pilots to make precise and sometimes quick decisions.

How Much Visibility Is Needed to Take Off and Land a Plane?

The visibility needed to land a plane depends on several factors, including the type of aircraft, the airport’s equipment, and weather conditions. Let’s examine the general requirements and specific conditions for Nepalese airports:

General Visibility Requirements

  • Takeoff Visibility: Most commercial aircraft require a minimum visibility of 400 meters for takeoff. However, some airports with advanced Instrument Landing Systems (ILS) may allow operations with lower visibility.

  • Landing Visibility: The minimum visibility for landing varies but typically ranges between 800 meters and 4,800 meters. Advanced systems like Category III ILS can enable landings with visibility as low as 75 meters.

Visibility at Nepalese Airports

  • Kathmandu Airport: The airport uses ILS to assist landings during poor visibility in aviation conditions. However, pilots must have at least 1,600 meters of visibility for safe operations under standard conditions.

  • Pokhara Airport: With limited advanced navigation systems, the visibility of Pokhara airport typically requires 3,000 meters for safe landings.

  • Bhairahawa Airport: Equipped with modern technology, the visibility of Bhairahawa Airport is generally sufficient for operations with 2,000 meters of visibility, even during foggy conditions.

Conclusion

While flight delays due to weather conditions may be frustrating, it is extremely important to understand the visibility needed to land a plane to appreciate the steps taken for flight safety. Due to the varying topography of Nepal, every airport experiences different weather patterns making it more challenging to predict weather. However, the Nepali aviation-sphere has gone above and beyond to incorporate advanced tools, training, and standards to avoid visibility in aviation being a stopping point and overcome challenges posed by low visibility in aviation. With continuous advancements in navigation systems, the risks associated with poor visibility in aviation can be effectively mitigated, making the skies safer for everyone. 

FAQ 

What are the types of visibility in aviation?

The three main types of visibility in aviation are Runway Visual Range (RVR), Meteorological Visibility, and Slant Visibility. Each type provides specific information critical for safe flight operations.

How much visibility do you need to land a plane?

The visibility needed to land a plane varies depending on the equipment and weather conditions. Standard requirements range from 800 meters to 4,800 meters.

What is the minimum flight visibility required?

The minimum flight visibility required for takeoff is generally 400 meters while landing visibility can range from 800 meters to 3,000 meters, depending on the airport and aircraft.