Tremor is a common phenomenon, but not all tremor is created equal. For pilots navigating the Federal Aviation Administration (FAA) medical certification process, distinguishing between a benign physiologic tremor and a pathologic Essential Tremor (ET) is critical. Here’s a breakdown of what ET really is, why it matters, and how a firm diagnosis may allow for continued flying (including via the CACI program or a special-issuance pathway) even when tremor has raised red flags.

What is Essential Tremor and how is it different from physiologic tremor

Tremor describes an involuntary, oscillatory movement of a body part. American Academy of Family Physicians (AAFP) guidance classifies tremors broadly into resting tremors (body part relaxed) and action tremors (body part voluntarily contracted, e.g., when outstretched, moving, holding a posture, or performing a task).[1]

• Physiologic tremor — everyone has a baseline tremor: low amplitude, high frequency, present at rest and during action. In healthy individuals it’s usually subclinical (you may not notice it) but can become momentarily apparent or worsened under stress, fatigue, caffeine intake, certain medications, or anxiety.[1]
• Essential tremor (ET) is a pathologic action tremor. It usually manifests when performing a movement or action (with arms outstretched, holding objects, handwriting, performing tasks), and is often bilateral and persistent. It may also affect the head, voice, lower extremities not just the hands.[1]

Unlike physiologic tremor, ET tends to worsen over time, can interfere with daily activities (e.g., holding a cup, writing, fine motor tasks), and often persists regardless of stress or external triggers.[1]

Why a firm diagnosis matters

Mischaracterizing a tremor as benign (or vice versa) is more than semantics — it has real implications for safety, medical certification, and proper management.

• Many tremors result from other neurologic disorders: drug- or metabolic-induced tremor, cerebellar disease, dystonic tremor, or degenerative conditions (e.g., parkinsonism).[1]
• A diagnosis of ET is often by exclusion meaning that other causes need to be considered and ruled out.[1] This is important for FAA medical certification!
  
• Studies show that a substantial fraction, some sources suggest 30–50%, of individuals initially labeled with ET are ultimately re-diagnosed with a different tremor disorder after neurologic re-evaluation.[1]
• For pilots, that means if tremor is not properly evaluated (history, physical exam, possibly imaging or further neurologic workup), an improper diagnosis could conceal a more serious neurological disorder which has implications for flight safety and medical certification.

FAA Approach: What the CACI Worksheet Says about Essential Tremor

The FAA’s “Tremor” guidance for Aviation Medical Examiners (AMEs) outlines how physiologic tremor and essential tremor are treated differently.

• Physiologic tremor: The guidance explicitly states that physiologic tremor is not a disease. If a pilot’s tremor appears to be physiologic, has no functional limitations and no medication dependence, and the AME judges there is no interference with flight duties, the pilot may be issued a certificate with “no time limitation.” [2]
• Essential Tremor (CACI-eligible): If a pilot has ET, the AME may use the CACI Worksheet only if ALL of the following criteria are met:[2]
  1. A current (within 90 days) detailed clinical progress note from the treating physician or neurologist confirming the diagnosis and stating that the ET is stable (no progression, no treatment changes recommended).[2]
  2. No evidence of disabling tremor (i.e., tremor does not significantly impair daily functioning — e.g., holding a cup, writing, flipping switches).[2]
  3. The applicant is not dependent on medication to function without disabling tremor (i.e., tremor remains non-impairing even off medication or when medication effect wanes).[2]
  4. If medication is used, it must be a beta-blocker (e.g., propranolol, metoprolol). Other medications, including primidone (Mysoline), gabapentin, use of weighted gloves or specialized utensils, or use of a deep brain stimulator, are not acceptable under the CACI for ET.[2]

If these criteria are satisfied, the AME may annotate in Block 60 “CACI qualified Essential Tremor” and the pilot can receive a certificate via CACI without submitting all documents to the FAA.[2] This is where it is crucial to have a quality detailed clinical progress note that shows a proper diagnosis and rules out other potentially concerning neurological conditions. 

What If You Don’t Meet CACI Criteria — Special Issuance Is Still an Option

Not meeting CACI criteria does not automatically mean you are grounded. The FAA still allows for certification via a special issuance pathway. This is especially relevant when ET is more severe, or requires non–beta-blocker therapy. 

The official FAA “Tremor” guidance clarifies that when tremor is disabling, progressing, dependent on non-CACI-eligible treatment (or assistive devices), or when diagnosis is uncertain the AME must defer.[2] If well managed, you may still be eligible for a medical certificate. 

Why It’s Critical to Get a Firm Diagnosis

From a clinical standpoint: correctly identifying ET versus another tremor disorder ensures proper care, monitoring, and treatment. Diagnoses may change over time; what starts as suspected ET might evolve, or reveal features of a different movement disorder. 

If the diagnosis is something other than ET, such as Parkinson’s Disease, the FAA has specific certification requirements that may differ from ET. Any unexplained neurological condition is a CFR mandatory disqualifying condition. 

For Pilots With Tremor

• Not all tremor means a disqualifying neurologic disease: physiologic tremor is benign, common, and acceptable — potentially allowing medical issuance with no time limit if no functional impairment is identified.
  
• Essential Tremor, when stable, non-disabling, and properly documented — especially with beta-blocker therapy only — can qualify under CACI.
  
• If your tremor doesn’t meet CACI requirements, a special-issuance remains viable, provided you’re willing to undergo the necessary neurologic workup and documentation.
  
• If your diagnosis is uncertain, do not go to an AME for an exam until it is! And make sure you are following the appropriate protocol for your actual diagnosis. Perhaps consider consulting with a professional on medical certification if you are uncertain which path to follow.

[1] P. Crawford and E. E. Zimmerman, “Tremor: Sorting Through the Differential Diagnosis”, Accessed: Nov. 30, 2025. [Online]. Available: https://www.aafp.org/pubs/afp/issues/2018/0201/p180.html 

[2] “FAA Tremor.” Jan. 25, 2023. Accessed: Nov. 30, 2025. [Online]. Available: https://www.faa.gov/ame_guide/media/Tremor.pdf